FUMIGATION 
METHODS 


A  Practical  Treatise  for  Farmers,  Fruit 
Growers,  Nurserymen,  Gardeners, 
Florists,  Millers,  Grain  Dealers,  Trans- 
portation Companies,  College  and 
Experiment  Station  Workers,  etc. 


By  WILLIS  G.  JOHNSON 

Formerly  Professor  of  Entomology  and  Invertebrate  Zoology  at  the 
Maryland  Agricultural  College  and  Stale  Entomologist;  author  of 
many  special  reports  on  economic  topics;  associate  editor  A  merican 
Agriculturist  weeklies  ;  Fellow  in  the  American  Association  for  the 
Advancement  of  Science;  Member  of  the  Association  of  Economic 
Entomologists,  the  A  merican  Pomological  Society,  the  Society  for 
the  Promotion  of  Agricultural  Science,  etc.  :  :  :  :  :  :  :  :  : 


ILLUSTRATED 


NEW    YORK 

ORANGE    JUDD    COMPANY 

1902 


COPYRIGHT,  1902 
BY  ORANGE  JUDD  COMPANY 


TABLE  OF   CONTENTS 


CHAPTER  I 

PAGE 

ECONOMIC  USE  OF  HYDROCYANIC  ACID  GAS       .        .          1-8 

Early  history — First  use  as  an  insecticide — 
Experiments  in  California — Dry  gas  process 
— Inauguration  of  night  fumigation — First  use 
in  Eastern  orchards. 

CHAPTER  II 
How  THE  GAS  is  MADE 9-11 

Chemical  ingredients — Combination  of  chem- 
icals —  Action  of  chemicals — Vessel  used  for 
generation — Character  of  residue  formed. 

CHAPTER  III 
PHYSIOLOGICAL  EFFECTS  ON  PLANTS    ....       12-24 

Experiments  by  Woods  and  Dorsett — Practi- 
cal tests  upon  orchard  trees  and  nursery  stock 
— Effects  on  seeds  and  low-growing  plants. 

CHAPTER  IV 

EFFECTS  ON  ANIMAL  LIFE 25-26 

Fortunate  accident — Chickens  pick  up  cyanide 
shaken  from  a  bag — Cat  destroyed  in  green- 
house while  asleep — Experiences  with  various 
animals. 

CHAPTER  V 
APPARATUS  FOR  USE  IN  ORCHARDS      ....      27-34 

Early  types  for  fumigators — Construction  of 
sheet  tents — Oiling  and  painting  tents — Vege- 
table decoction  for  treating  tents. 

CHAPTER  VI 

BELL  AND  HOOP  TENTS 35~47 

General  description — Method  of  handling — 
The  hoop  tent  popular  in  California — Construc- 
tion and  manipulation. 

iii 


iv  FUMIGATION   METHODS 

PAGB 
CHAPTER  VII 

CONSTRUCTION  AND  MANAGEMENT  OF  SHEET  TENTS  .      48-58 

Methods  of  making  and  handling  sheet  tents 
— Apparatus  used  in  Eastern  orchards — De- 
scription of  California  outfit. 

CHAPTER  VIII 
EMORY  FUMIGATOR  WITH  MODIFICATIONS   .        .        ,       59-75 

Development  of  the  Emory  fumigator — Gen- 
eral description — Apparatus  for  handling — Cost 
of  construction — The  Miller  type — Method  of 
operating — The  New  York  box  fumigator. 

CHAPTER  IX 
ESTIMATING  GAS  FOR  ORCHARD  WORK        .        .        .      76-83 

Amount  of  chemicals — Cyanide  necessary — 
Destroying  black  scale  on  citrus  trees — Red, 
brown,  and  purple  scale — Orchards  on  damp 
grounds  —  Eastern  orchards  —  Comparative 
value  of  cyanide. 

CHAPTER  X 

DAYLIGHT  FUMIGATION  AND  COST  OF  APPLICATION  .      84-92 

Experiences  in  Eastern  orchards  —  Expert 
opinion  from  California — Time  of  application — 
— Cost  of  orchard  fumigation — Location  of  or- 
chard considered. 

CHAPTER   XI 

EQUIPMENT  FOR  FUMIGATING  NURSERY  STOCK        .        93-111 

Conditions  considered — Construction  and  use 
of  boxes — How  to  build  a  fumigatorium — Vari- 
ous types  described. 

CHAPTER   XII 
CONSTRUCTION  OF  VENTILATORS  AND  FLOORS        .        112-117 

Form  used  in  Canada — Arrangement  em- 
ployed in  Ohio — Method  in  Delaware — A 
Western  idea. 

CHAPTER   XIII 
PRACTICAL  HINTS  TO  NURSERYMEN         .        .        .        118-125 

Estimating  chemicals — Low-grade  stock — Cost 
of  nursery  stock  fumigation — Value  of  small 
room — Preparation  of  trees — Materials  needed 
— Cellars  and  cars — Use  of  canvas  over  wagon 
— Points  to  remember. 


OF  CONTENTS  V 

CHAPTER    XIV 

GREENHOUSE  AND  COLD  FRAME  FUMIGATION         .        126-146 

Effects  on  foliage — Preparation  of  the  house 
— How  to  prepare  the  jar — Boxes  for  fumigat- 
ing small  plants — Experiences  with  various 
plants — Experiments  in  greenhouses — Estimat- 
ing cubic  contents — Cold  frames — General  sum- 
mary— Practical  application. 

CHAPTER   XV 

SMALL  FRUITS  AND  PLANTS 147-152 

Amount  of  chemicals  for  strawberry  plants — 
Experimental  and  practical  tests — Application 
on  melon,  cucumber,  cabbage,  etc. — Difficulty 
of  fumigating  in  rows. 

CHAPTER   XVI 

APPLICATIONS    IN    MILLS,    ELEVATORS,    AND    OTHER 

ENCLOSURES 153-176 

First  use  in  mills — Necessary  preparations — 
Resisting  power  of  insects — Estimating  chemi- 
cals— Application — Cars  and  ships — Dwelling- 
houses  and  storerooms — Explosive  properties — 
Practical  application — Mills  and  elevators — 
Tobacco  warehouse — Houses  and  Laboratories. 


CHAPTER   XVII 

GRAINS  AND  OTHER  SEEDS 177-185 

Experimental  tests — Influence  upon  seed 
germination — Fumigated  grain  fed  to  mice — 
Effects  on  dry  and  damp  seeds — General  sum- 
mary of  results. 


CHAPTER   XVIII 

DIFFUSION  OF  HYDROCYANIC  ACID  VAPOR     .        .        186-197 

General  experiments — Effect  of  moisture  on 
foliage — Absorbent  effect  of  fresh  earth — Dif- 
fusion in  large  room — Rapid  loss  of  vapor — 
General  results  considered. 


vi 


FUMIGATION  METHODS 
CHAPTER   XIX 


RECENT  WORK  WITH  HYDROCYANIC  ACID  GAS      .        198-220 

Successful  application  in  England — Vineries 
and  Conservatories — Use  on  ordinary  green- 
house pests — Use  in  New  South  Wales — Cost  of 
material  for  tents — Orchard  work  in  Cape 
Colony — Experiments  at  New  York  Agricul- 
tural Experiment  Station — Fumigation  of  or- 
chard trees. 

CHAPTER    XX 
ECONOMIC  VALUE  OF  FUMIGATION  .        .        .        221-256 

First  use  upon  nursery  stock — Fumigating 
greenhouses — Olive  trees  fumigated — Fumiga- 
tion understood  and  appreciated — The  superi- 
ority of  fumigation — Operations  in  Canada — 
Form  of  fumigating  box — Common-sense  views. 

CHAPTER   XXI 

FUMIGATION  WITH  CARBON  BISULPHID  .        .        257-284 

First  use  to  destroy  insects^Chemical  proper- 
ties— Commercial  uses — Instruments  for  appli- 
cation— Fumigating  mills  and  other  buildings — 
Practical  work — Precautions — Effects  upon 
seeds — Fruits  and  plants — Destroying  pests  in 
woolens,  furs  and  clothes — Killing  prairie-dogs, 
gophers,  squirrels,  etc. — Expert  opinions  of  its 
practical  value — Exterminating  rats  and  mice — 
How  it  is  put  up. 

CHAPTER   XXII 

LAWS  REGULATING  NURSERY  AND    ORCHARD    INSPEC- 
TION AND  FUMIGATION 285-302 

General  review  of  the  situation  in  the  United 
States — Abstracts  of  State  Laws. 


CHAPTER   XXIII 

FOREIGN  LAWS    REGULATING   SHIPMENTS    OF    FRUITS 
AND  NURSERY  STOCK         .        .        .        . 

Abstracts  of  the    Foreign  Regulations — List 
of  ports  of  entry. 


303-309 


ILLUSTRATIONS 


PAGE 

Portrait  of  the  Author        ....         Frontispiece 
York  Imperial  Apple  Tree,  Fumigated   with  Six  Times 

Normal  Dose          ........  17 

Ogon  Plum,  Fumigated  with  Three  Times  Normal  Dose  18 

Ogon  Plum  Tree, .Fumigated      ......  19 

Peach  Tree,  Fumigated  with  Normal  Dose         ...  21 
Effects  of  Gas  on  Mature  Peach  Trees,  where  Overdoses 

were  Used      .........  23 

The  Wolfskill  Fumigator 29 

The  Titus  Fumigator  ........  30 

The  Culver  Fumigator         .......  31 

Culver  Tent  and  Morse  Fumigator     .....  32 

Canvas  Tent  with  Square  Top  and  Base    ....  33 

The  Preble  Fumigator,  as  Used  in  California  Orchards  .  36 

Raising  Small  Hoop  Tent    .......  37 

Hoop  Tent  Almost  in  Position 38 

Small  Hoop  Tent  Ready  for  Chemicals      .         .         .         .  39 

Lifting  Large  Hoop  Tent  from  Ground      ....  40 

Adjusting  Large  Hoop  Tent 41 

Lifting  Tent  After  Fumigation  .         .         .    •     .         .         .43 

Covering  Tree  with  Large  Hoop  Tent        ....  44 

Method  of  Shifting  Large  Hoop  Tent.  (After  Woodworth)  45 

Orchard  Work  with  Sheet  Tents  in  the  East      ...  47 
Manipulating   Sheet  Tents  with    a  Single  Pole.     (After 

Woodworth)  .........  48 

Handling  a  Tent  with  a  Single  Pole 49 

Removing  Sheet  Tent  by  Means  of  Pole  and  Helpers       .  50 

Covering  Large  Orange  Trees  with  a  Sheet  Tent     .         .  51 
Sheet  Tent  in  Position  Over  an  Orange  Tree  Ready  for 

Chemicals       .........  53 

vii 


viii  FUMIGATION  METHODS 

PACK 

^Removing  Sheet  Tent,  Assisted  by  a  Horse  ...  55 

Fumigating  Apparatus  Readyjor  Transportation  .  .  56 

Tenting  an  Orange  Tree  in  California  ....  57 

Tent  in  Position  about  Ready  for  Chemicals  ...  58 
Model  Type  of  Emory  Fumigator  with  Hood  Fully 

Extended        .........  60 

Practical  Work  with  the  Emory  Fumigator  .  .  .  61 

Folding  Paper  Fumigator  compared  with  Sheet  Tent  .  62 

Apparatus  for  Manipulating  the  Emory  Fumigator  .  63 

Fumigating  an  Orchard  on  a  Mountain  Side  ...  65 
Practical  Application  of  the  Emory  Fumigator  on  Rough 

Land 67 

Placing  Fumigator  Over  Tree,  Showing  also  Tray  for 

Chemicals 68 

Fumigator  Nearly  in  Position     ......  69 

Placing  the  Chemicals  Under  Fumigator  ....  70 

Airing  the  Fumigator  Just  Before  Removal      ...  40 

Transferring  the  Fumigator        ......  73 

Fumigator  Designed  at  the  New  York  Experiment 

Station 74 

Japanese  Plum  Tree,  Fumigated  in  October  ...  85 

Charging  a  California  Hoop  Tent  .....  89 

Wagon  for  Carrying  Chemicals  in  Orchard  ...  91 

Box  Used  by  a  Nurseryman  in  the  South.  (After  Sherman)  94 
Type  of  Box  Used  by  a  Canadian  Nurseryman.  (After 

Lochhead)      .........  95 

The  Open  Box  Used  in  Some  Maryland  Nurseries. 

(Original)        .........  96 

Open  Box  Reversed  Ready  for  Chemicals.     (Original)    .  97 

Large  and  Convenient  Fumigatorium         ....  98 

Room  Where  Trees  are  Fumigated  by  the  Wagon  Load  .  99 

Double  Rooms  Built  in  End  of  Packing-shed  .  .  .  100 

Single  Room  Used  in  Winter  for  Grafting  .  .  .  101 
Neatly  Constructed  Single  Room  with  Corrugated  Iron 

Roof 102 

Handy  and  Cheap  House  for  Small  Nursery  .  .  .  103 

Outline  of  Model  Fumigating  House.  (Original)  .  .  104 

Plan  for  Slat  Floor.  (Original) 104 


ILLUSTRATIONS  ix 

PAGE 

General  Plan  of  Floor.  (Original)  .....  105 

Where  Trees  are  Fumigated  by  the  Million  .  .  .  106 

Well-built  Single-room  House  for  Small  Nursery  .  .  106 

Complete  Fumigating  House  in  Utah  ....  107 

Sectional  View  of  a  Model  Utah  House.  (After  Moore)  .  108 
Double  House  in  Canada  for  Fumigating  Trees  on  a 

Wagon 109 

Fumigating  House  at  the  Ontario  Agricultural  College  .  no 
Methods  of  Ventilating  a  Fumigating  House.  (After 

Lochhead)      .........  112 

Diagram  of  Generator  and  Sectional  View  of  Fumiga- 

torium.  (After  Webster) 113 

Lower  Portion  of  Fumigatorium.  (After  Sanderson)  .  114 

Generator  and  Details  for  Handling.  (After  Sanderson)  115 

Method  of  Fumigating  Greenhouse  .....  129 

Box  for  Fumigating  Small  Plants  and  Cuttings  .  .  131 
Diagram  for  Determining  Cubic  Contents  of  Greenhouse. 

(After  Galloway)  ........  140 

Even  and  Three-quarter  Space  Houses.  (After  Woods 

and  Dorsett)  .........  142 

Interior  Arrangement  for  Fumigating  Buildings.  (Orig- 
inal) . (  .  .  .  164 

Fumigating  in  a  New  South  Wales  Orchard  .  .  .  204 

Two  Orange  Trees,  Fumigated  and  not  Fumigated.  .  205 
Average  Specimen  of  Orchard  Fruit  from  a  Fumigated 

Tree 207 

Average  Specimen  of  Orchard  Fruit  from  a  Tree  not 

Fumigated      .........  207 

Improved  Method  of  Fastening  Door  on  the  Lowe  Fumi- 

gator 215 

The  Sirrine  Type  of  Folding  Fumigator  ....  217 

Canvas  Tent  with  Felt  Type  of  Pyramidal  Hood  .  .  219 

Fumigated  Citrus  Orchard  in  California  ....  222 

Sprayed  Orange  Tree  in  a  California  Orchard  .  .  .  223 


PUBLISHER'S  PREFACE 


T  was  the  original  plan  of  the  author  to  have 
used  as  a  frontispiece  in  this  work  a  portrait 
of  Mr.  D.  W.  Coquillett,  who  discovered  the 
economic  value  of  hydrocyanic  acid  gas  as  an 
insecticide.  Mr.  Coquillett  prefers  to  be  remembered 
by  the  discovery  he  made  in  his  experimental  and  prac- 
tical work  with  hydrocyanic  acid  gas.  The  publishers 
therefore  take  pleasure  in  introducing  this  volume 
with  a  portrait  of  the  author,  who  has  done  so  much 
to  utilize  in  a  practical  way  the  discovery  made  by  Mr. 

Coquillett. 

ORANGE  JUDD  COMPANY. 


AUTHOR'S    PREFACE 


CE  radical  changes  in  conditions  during  the 
past  eight  or  ten  years  along  agricultural  and 
commercial  lines  have  been  followed  by  the 
general  distribution  of  many  insect  pests  of  a 
serious  character.  In  commercial  transactions  the  dan- 
gers have  been  so  great  along  certain  lines  that  many 
State  laws  have  been  enacted  to  prohibit  the  distribu- 
tion of  such  insects  as  the  San  Jose  scale  and  others  of 
a  dangerous  nature.  Some  foreign  governments  have 
enacted  such  legislation  as  to  make  it  practically  im- 
possible to  ship  fruit  and  nursery  stock  without  the 
most  rigid  inspection  and  fumigation  before  entry  is 
permitted. 

Ability  to  successfully  combat  noxious  insects  is  a 
problem  of  the  most  vital  importance  to  farmers,  fruit 
growers,  nurserymen,  gardeners,  florists,  millers,  grain 
dealers,  transportation  companies,  merchants,  grocers, 
housekeepers  and  others.  This  is  especially  true  of 
the  fruit,  nursery,  and  grain  industries.  The  use  of 
hydrocyanic  acid  gas  and  carbon  bisulphid,  two  very 
powerful  insecticides,  have  largely  solved  these  serious 
problems.  We  owe  the  discovery  of  carbon  bisulphid 
as  an  insecticide  to  M.  Doyere,  while  that  of  hydrocyanic 
acid  gas  belongs  to  D.  W.  Coquillett.  Their  practical 
application  has  been  one  of  gradual  development. 

With  the  advent  of  the  San  Jose  scale  in  Eastern 


XIV  FUMIGATION   METHODS 

nurseries  and  orchards  the  demand  for  exact  informa- 
tion about  a  cheap  and  reliable  remedy  became  a  live 
topic.  Little  or  nothing  had  been  done  with  hydro- 
cyanic acid  gas  fumigation  outside  of  California. 
From  what  the  writer  had  observed  in  California,  he 
was  certain  that  this  method  wras  the  most  promising 
and  would  meet  the  conditions  in  the  Hast  and  other 
places  if  properly  adapted.  Hundreds  of  experiments 
and  practical  applications  were  made  by  the  writer  to 
test  the  gas  in  orchards,  nurseries,  greenhouses,  mills, 
warehouses,  granaries,  and  various  other  places.  The 
outcome  of  these  tests  proved  conclusively  that  hydro- 
cyanic acid  gas  was  a  cheap  and  reliable  remedy  for  a 
very  large  range  of  insects  usually  found  in  such  places. 

In  the  present  volume  the  writer  has  attempted  to 
embody  the  practical  results  of  his  own  experiences  as 
well  as  those  of  others  who  have  used  these  gases  suc- 
cessfully. In  his  endeavors  to  gather  together  the 
fragmentary  notes,  scattered  as  they  were  in  litera- 
ture throughout  the  world,  the  author  feels  that  this 
work  is  not  complete  and  perfect  in  every  respect.  It 
embraces,  however,  for  the  first  time  in  one  volume, 
a  general  survey  of  this  important  and  timely  subject. 

Where  the  writer  has  not  given  personal  credit  in 
the  text  he  wishes  to  extend  the  same  courteous 
acknowledgment  to  all  who  have  in  any  way  con- 
tributed to  the  contents  of  this  volume.  Hspecial 
thanks  are  due  to  Mr.  D.  W.  Coquillett  for  reading 
and  correcting  proofs,  and  to  Mr.  Herbert  Myrick, 
Editor  and  Proprietor  of  the  Orange  Judd  weeklies  and 
books,  through  whose  aid  and  courtesy  this  volume  is 
written  and  published. 


AUTHOR'S  PREFACE  xv 

All  the  illustrations  reproduced  herewith  are  from 
photographs  taken  by  the  author,  excepting  those 
acknowledged  below  or  credited  in  the  text.  To  the 
following  the  author  desires  to  express  his  thanks  :  to 
the  Secretary  of  the  California  State  Board  of  Horti- 
culture, for  photographs  and  drawings  from  which 
Figs.  8  to  ii  inclusive,  13,  30  and  31  were  reproduced; 
to  the  Director  of  the  California  Experiment  Station, 
for  permission  to  use  electrotypes  of  Figs.  14  to  21  in- 
clusive, 23,  45,  and  46  ;  to  Mr.  R.  P.  Cundiff,  Horti- 
cultural Commissioner  Riverside  District,  California, 
for  photographs  of  Figs.  26,  27,  28,  and  29  ;  to  the 
Director  of  the  New  York  Agricultural  Experiment 
Station,  for  permission  to  use  photographs  of  Figs.  43, 
79,  and  80  ;  to  the  Secretary  of  the  Pennsylvania  State 
Board  of  Agriculture,  for  loan  of  electrotypes  of 
author's  photographs;  to  Mr.  D.  M.  Moore,  of  Utah, 
for  photograph  from  which  Fig.  62  was  made;  to  Prof. 
William  Lochhead,  of  the  Ontario  Agricultural  Col- 
lege, for  photographs  of  Figs.  64  and  65  ;  to  Mr.  W. 
J.  Allen,  of  New  South  Wales,  for  use  of  Figs.  75,  76, 
77,  and  78 ;  to  Dr.  E.  P.  Felt,  State  Entomologist  of 
New  York,  for  photograph  of  Fig.  81,  and  finally  to 
Mr.  C.  M.  Heintz,  editor  of  the  Rural  Calif ornian, 
for  photographs  from  which  Figs.  82  and  83  were 
reproduced. 

Although  the  author  has  taken  unusual  pains  to 
make  this  work  technically  correct  yet  popular  in 
style,  there  have,  no  doubt,  crept  in  some  mistakes. 
When  readers  note  any  error,  typographically  or  oth- 
erwise, they  will  confer  a  great  favor  on  the  writer  by 
reporting  same,  so  corrections  can  be  made  in  future 


XVI  FUMIGATION   METHODS 

editions.  If  this  volume  will  in  any  way  answer  the 
numerous  questions  asked  on  the  subject  of  fumiga- 
tion, either  with  hydrocyanic  acid  gas  or  carbon  bisul- 
phid,  or  suggest  methods  for  future  work  along 
these  lines,  the  writer  will  feel  repaid  for  his  labors. 

Wnjjs  G.  JOHNSON. 

NEW  YORK  CITY, 

February  75,   igos. 


FUMIGATION    METHODS 


CHAPTER    I 
ECONOMIC    USE    OF    HYDROCYANIC    ACID    GAS 

T"HHK  discovery  of  the  value  of  hydrocyanic  acid 
gas  as  an  insecticide  was  due  to  the  presence 
of  the  cottony  cushion  scale  in  the  citrous 
orchards  of  California.  This  insect  was  un- 
wittingly introduced  into  California  from  Australia. 
For  a  time  it  seemed  certain  that  the  pest  would  ruin 
the  orange  and  lemon  industry  in  spite  of  the  con- 
certed efforts  of  the  most  intelligent  horticulturists  to 
combat  it.  Despairingly,  the  growers  appealed,  as  a 
last  resort,  to  the  United  States  Department  of  Agri- 
culture for  aid.  The  matter  was  taken  up  by  the 
Division  of  Entomology,  and  two  assistants  were 
detailed  by  Dr.  C.  V.  Riley,  then  Entomologist,  to 
undertake  the  study  of  methods  for  the  control  of  the 
insect.  These  assistants  were  D.  W.  Coquillett  and 
A.  Koebele.  To  Mr.  Coquillett  belongs  the  credit  of 
first  discovering  the  value  of  hydrocyanic  acid  gas, 
now  so  extensively  used,  for  the  destruction  of  insects 
and  other  animal  pests. 

In  addition  to  the  detailed  account  of  the  gas  treat- 
ment given  by  Mr.  Coquillett,  in  the  report  of  the 


2  FUMIGATION   METHODS 

Department  of  Agriculture  for  1887,  and  in  "Insect 
Life,"  Vol.  III.,  by  way  $>f  explanation,  he  wrote  me 
March  21,  1898,  as  follows  :  "  During  the  summer  of 
1886  I  was  employed  by  the  United  States  Depart- 
ment of  Agriculture  to  carry  on  a  series  of  experiments 
at  lyos  Angeles,  California,  against  the  cottony  cushion 
scale  {Icerya  purchast),  but  owing  to  an  insufficient 
appropriation  I  was  laid  off  on  August  ist  of  that 
year.  As  no  perfect  remedy  had  at  that  date  been 
discovered,  I  determined  to  experiment  with  gases 
in  a  private  capacity  and  at  my  own  expense. 
Accordingly,  during  the  first  wfeek  of  the  following 
month  I  began  experimenting  with  hydrocyanic  acid 
gas,  which  I  thought  would  be  the  best  for  the  pur- 
pose, owing  to  its  very  poisonous  qualities,  the  rapidity 
of  its  generation,  and  the  readiness  with  which  it  dif- 
fuses itself  in  the  air.  Nobody  suggested  to  me  to 
try  this  gas.  It  was  not  until  the  following  July  that 
the  Department  of  Agriculture  again  placed  me  on  its 
rolls." 

It  will  thus  be  seen  that  Mr.  Coquillett  continued 
to  work  on  the  problem  of  destroying  the  scale,  though 
at  his  own  expense,  and  in  September,  1886,  began 
seriously  to  study  the  methods  of  fumigation.  Fumi- 
gation with  carbon  bisulphide  had  been  inaugurated 
on  a  small  scale  by  J.  W.  Wolf  skill  and  his  very  able 
foreman,  Alexander  Craw,  at  L,os  Angeles.  At  their 
place  Mr.  Coquillett  began  his  experiments,  profiting 
by  the  facilities  here  provided.  It  was  here  he  first 
conceived  the  idea  of  using  hydrocyanic  acid  gas. 
About  six  months  were  required  to  perfect  methods. 

The  result  of  the  work  in  the  Wolf  skill  orchards 


ECONOMIC  USE   OF   HYDROCYANIC   ACID   GAS         3 

was  watched  with  keen  interest  by  those  whose  trees 
were  fast  being  ruined  by  the  scales.  Many  growers 
became  impatient  to  know  the  remedy  so  carefully 
guarded  by  the  experimenters.  Finally,  a  number  of 
horticulturists  about  San  Gabriel  asked  Prof.  E.  W. 
Hilgard,  of  the  University  of  California,  for  a  chemist 
to  experiment  in  their  orchards  with  various  gases. 
F.  W.  Morse  was  detailed  for  this  work,  and  found, 
like  Mr.  Coquillett,  that  hydrocyanic  acid  gas  was  by 
far  the  most  satisfactory.  In  the  course  of  these  ex- 
periments certain  parties  who  had  witnessed  the  former 
experiments  recognized  the  odor  of  gas,  and  thus  the 
secret,  so  zealously  guarded,  was  given  to  the  public. 
Although  discovered  and  used  by  Mr.  Coquillett  and 
his  associates  six  months  previous  to  the  announce- 
ment of  Mr.  Morse,  the  first  general  information  about 
the  gas  as  an  insecticide  was  given  to  the  public  by 
the  latter  gentleman  in  a  Bulletin  (No.  71)  from  the 
University  of  California  Experiment  Station. 

Extensive  experiments  were  continued  by  Mr. 
Coquillett.  In  July,  1887,  he  was  again  made  an 
assistant  of  the  Department  of  Agriculture,  and  did 
more  than  any  other  person  to  develop  and  perfect  the 
present  methods  of  fumigation.  The  main  difficulty 
encountered  in  these  early  experiments  was  the  inju- 
rious effect  the  gas  had  upon  the  foliage.  The  injury 
was  lessened  greatly  by  the  ' '  soda  process ' '  of  Morse, 
which  consisted  in  adding  ordinary  baking  soda  to  the 
cyanide  solution,  using  something  like  two  and  a  half 
times  as  much  soda  as  there  was  cyanide  in  the  solu- 
tion, the  result  being  the  production  of  carbonic  acid 
gas,  thus  diluting  the  hydrocyanic  acid  gas. 


4  FUMIGATION   METHODS 

Speaking  of  the  early  experiences  with  this  gas, 
Prof.  C.  W.  Woodwork  says  that  previous  to  the 
time  of  the  publication  of  Morse's  soda  method,  Mr. 
Coquillett  accomplished  a  similar  diminution  of  injury 
by  slow  generation  of  the  gas.  This  Mr.  Coquillett 
accomplished  by  means  of  a  generator  consisting  of  two 
parts:  from  one  the  sulphuric  acid  passed  in  a  fine 
stream,  regulated  by  a  stop-cock,  into  the  other  con- 
taining dry  cyanide.  These  facts  were  clearly  set  forth 
by  Alexander  Craw  in  a  paper  before  a  meeting  of 
fruit  growers  at  I,os  Angeles,  in  October,  1887. 

The  ' '  dry  gas  process  ' '  was  soon  devised  by  Mr. 
Coquillett.  It  consisted  in  passing  the  gas  from  the 
generator  through  sulphuric  acid,  allowing  it  to  come 
in  contact  with  the  foliage.  In  this  he  used  a  solution 
of  cyanide.  This  was  the  situation  at  the  time  of  the 
publication  of  Mr.  Coquillett 's  first  paper,  cited  above, 
wherein  these  three  processes  were  described  quite 
fully.  He  strongly  recommended  his  last  process  as 
the  cheapest  and  most  convenient;  and  Mr.  Morse,  in 
a  later  paper,  practically  abandoned  his  soda  method  in 
favor  of  the  dry  gas  process. 

Injury  to  trees  from  the  first  has  been  a  specula- 
tion and  controversy,  and  even  now  it  must  be  con- 
fessed that  we  are  far  from  possessing  sufficient  data  to 
enable  us  to  solve  any  considerable  part  of  the  problem. 
The  results  have  been  very  uncertain,  proving  that 
there  are  a  number  of  factors  involved.  One  of  the 
earliest  explanations  suggested  was  that  faulty  dis- 
tribution of  the  gas  would  tend  to  cause  burning 
wherever  the  pure  or  slightly  diluted  gas  came  in  con- 
tact with  the  leaves.  Practical  experience  bore  out 


ECONOMIC  USE   OF   HYDROCYANIC   ACID   GAS         5 

this  idea,  so  that  in  most  of  the  earlier  work  elaborate 
provision  was  made  for  the  mixing  of  the  gas  and  the 
air  contained  in  the  tent.  Generally  some  form  of 
blower  connected  with  the  generator  was  used.  How- 
ever, later  work  has  demonstrated  that  this  is  of  minor 
importance. 

The  first  theory  of  Mr.  Coquillett  was  that  the 
mixing,  or  perhaps  the  combination,  of  the  gas  with 
water  rendered  it  more  injurious.  Both  of  his  proc- 
esses were  based  on  this  idea.  He  explained  the 
effectiveness  of  the  soda  process  as  arising  from  the 
affinity  of  the  carbonic  acid  for  water.  Mr.  Morse's 
original  ideas  are  not  made  plain  in  his  writings,  but 
his  later  studies  led  him  to  believe  that  the  develop- 
ment of  ammonia  in  the  gas  was  the  most  important 
cause  of  injury.  The  injurious  effects  of  ammonia 
are  well  known,  and  he  demonstrated  the  presence 
of  ammonia  in  the  gas,  especially  in  that  generated 
from  a  solution  of  cyanide.  Thus  there  were  two 
theories  accounting  for  the  good  effects  of  the  methods 
then  known,  and  both  agreed  in  favoring  the  dry  gas 
process.  The  latter  theory  seems  to  have  had  more 
foundation  in  fact,  but  it  soon  became  evident  that 
there  were  other  still  more  important  factors  determin- 
ing the  injury  to  the  foliage. 

The  successful  introduction  of  ladybirds  from  Aus- 
tralia into  California,  and  the  promising  results  of  the 
importation,  caused  the  gas  method  to  remain  at  a 
standstill  for  some  time.  The  interest  in  fumigation 
was  later  revived,  however,  on  account  of  the  red 
scale  {Aspidiotus  aurantii},  which  was  becoming  quite 
troublesome  in  many  orchards  in  Orange  County.  By 


6  FUMIGATION   METHODS 

invitation,  Mr.  Coquillett  took  his  apparatus  to  the 
orchards  of  A.  D.  Bishop,  and  commenced  a  new  series 
of  tests.  The  ones  giving  the  best  results  were  the 
same  as  some  of  Mr.  Coquillett's  earliest  experiments, 
in  which  the  gas  was  generated  in  a  simple  generator 
beneath  the  tent,  according  to  the  formula  now  gen- 
erally used. 

It  was  generally  believed  by  Mr.  Coquillett  at  this 
time  that  it  was  the  aclinic  rays  rather  than  the  heat 
rays  of  the  sun  that  injured  the  foliage.  It  had  been 
previously  noticed  that  trees  were  more  injured  during 
the  middle  of  the  day  than  at  other  times,  and  it 
was  usually  attributed  to  the  heat.  Working  on  his 
theory,  Mr.  Coquillett  began  experiments  with  a 
black  tent,  and  confirmed  his  belief  that  it  was  the 
aclinic  and  not  the  heat  rays  that  caused  the  trouble. 
Naturally,  night  work  in  fumigation  soon  followed. 
It  was  on  Mr.  Bishop's  place  where  the  first  practical 
night  fumigation  was  inaugurated.  The  success  of 
these  experiments  has  been  far-reaching.  The  adop- 
tion of  methods  here  perfected  has  been  quite  univer- 
sal. In  practical  results,  the  fumigation  at  night  is 
satisfactory  and  regarded  as  essential  to  good  fumiga- 
tion in  citrous  orchards.  Mr.  Bishop,  in  company 
with  some  neighbors,  applied  for  a  patent  on  the  proc- 
ess, which  was  granted,  even  in  the  face  of  a  strong 
protest  from  Mr.  Coquillett  and  Dr.  Riley  to  the  Com- 
missioner of  Patents.  L/ater,  however,  the  courts  de- 
cided that  the  process  was  not  patentable,  and  the 
controversy  ended. 

The  main  interests  centering  around  fumigation 
were  confined  mainly  to  California  until  1893.  ^n 


ECONOMIC  USK   OF   HYDROCYANIC   ACID   GAS          7 

August  of  that  year  the  San  Jose  scale  (Aspidiotus  per- 
niciosus  Comstock)  was  found  at  Charlottesville,  Va., 
on  the  grounds  of  Dr.  C.  H.  Hedges.  This  was  the 
first  discovery  of  this  pest  east  of  the  Rocky  Moun- 
tains, and  naturally  caused  a  good  deal  of  apprehen- 
sion on  the  part  of  fruit  growers  all  over  the  country. 
Again  Mr.  Coquillett  was  detailed  by  the  United  States 
Department  of  Agriculture  to  conduct  experiments 
with  hydrocyanic  acid  gas  on  these  infested  trees.  The 
work  was  begun  and  completed  in  March,  1894. 

The  gas  process  was  not,  however,  generally 
recommended  for  the  fumigation  of  deciduous  trees. 
From  the  experiences  of  growers  in  California  I  felt 
certain  that  the  gas  could  be  applied  equally  as  suc- 
cessful to  deciduous  fruit  trees  in  the  Bast  and  else- 
where, if  properly  handled.  With  practically  nothing 
as  a  guide,  except  the  general  work  done  in  California, 
and  little  or  no  encouragement  from  leading  Eastern 
entomologists,  I  began  a  series  of  experiments,  in  the 
spring  of  1897,  upon  young  plum,  pear,  apple,  and 
nectarine  trees.  The  results  of  these  preliminary  ex- 
periments were  so  very  satisfactory  that  I  was  prompted 
to  continue  my  work  on  bearing  trees  in  the  fall  of 
1897.  With  the  aid  of  Robert  S.  Emory,  of  Chester- 
town,  Md.,  a  successful  fruit  grower,  we  perfected  an 
outfit  and  completed  the  first  successful  fumigation  of 
a  large  orchard  in  the  East.  The  results  of  this  work 
were  watched  with  much  interest  in  this  and  other 
countries.  While  the  methods  of  generating  the  gas 
have  not  been  materially  changed,  the  amounts  of 
chemicals  have  been  adapted  to  suit  conditions.  The 
apparatus  for  containing  the  gas  has  bee"n  improved, 


8  FUMIGATION   METHODS 

and  the  box  system,  designated  by  me  as  the  "  Kmory 
Fumigator,"  has  been  perfected,  and  is  now  commonly 
used  by  orchardists  and  others. 

Since  1894  the  gas  nas  also  been  used  in  green- 
houses for  the  destruction  of  certain  pests.  The 
demand  for  fumigated  trees  led  me  to  conduct  an 
extensive  series  of  experiments  with  the  gas  upon 
nursery  stock  of  various  kinds  and  grades.  These 
tests,  begun  the  fall  of  1896  and  completed  the  spring 
of  1899,  have  shown  conclusively  the  maximum  and 
minimum  amount  of  gas  young  trees  will  withstand 
without  injury.  Many  obscure  points  about  the  con- 
struction and  management  of  fumigating  houses  have 
been  made  clear. 

In  1898  I  first  suggested  the  use  of  hydrocyanic 
acid  gas  as  a  remedy  for  the  destruction  of  insects  in 
mills,  elevators,  and  warehouses.  The  system  has 
since  been  perfected  under  my  direction,  and  it  is  now 
in  general  use  in  this  and  other  countries.  In  1900  I 
demonstrated  that  the  gas  could  be  used  in  tight 
buildings  with  perfect  success  and  .safety,  even  in  the 
thickly  populated  districts  of  a  city,  wThen  properly 
handled,  for  the  destruction  of  certain  pests,  including 
rats  and  mice.  The  fumigation  of  street-cars  and 
railroad  coaches  to  destroy  bedbugs  and  other  vermin 
is  commonly  practiced  in  many  places.  The  gas  is 
also  employed  to  rid  houses  of  undesirable  pests,  but 
in  such  cases  should  be  handled  with  great  care. 


CHAPTER  II 
HOW   THE  GAS  IS   MADE 

T|HK  chemicals  used  for  generating  hydrocyanic 
acid  gas  are  ( i )  fused  cyanide  of  potassium 
(KCN),  (2)  sulphuric  acid  (H2SO4),  and 
(3)  water  (H2O).  The  cyanide  should  be 
guaranteed  98-99  per  cent. ,  which  is  practically  chem- 
ically pure.  There  is  upon  the  market  in  some  places 
an  old  brand  of  cyanide  of  about  58—60  per  cent, 
purity.  This  should  be  avoided. 

The  best  grade  of  commercial  sulphuric  acid,  with 
a  specific  gravity  of  at  least  1.83,  should  be  used.  A 
grade  known  as  chamber  acid  used  ordinarily  in  the 
manufacture  of  fertilizers  will  not  do,  and  under  no 
circumstances  should  it  be  employed.  Water  from  any 
source  will  sufiice,  the  only  requisite  being  that  it 
should  be  clean. 

In  combining  the  chemicals  (i),  measure  the  acid  in 
the  glass  beaker  marked  ounces  on  the  side,  and  pour 
it  in  an  earthenware  crock,  wooden  bucket,  tub,  or 
pickle  jar;  (2),  measure  the  water  in  the  same  beaker 
and  pour  it  on  the  acid;  (3),  drop  in  the  cyanide,  bag 
and  all,  if  wrapped  in  paper,  close  the  door  or  drop  the 
tent  quickly,  and  leave  desired  length  of  time. 

Action  of  the  chemicals. — When  the  water  is  poured 
into  the  jar  upon  the  acid,  a  slight  evolution  of  steam 
arises,  which  is  not  dangerous.  As  soon  as  the  cyanide 
is  dropped  in  the  acid  and  water  there  is  a  bubbling 

9 


10  FUMIGATION   METHODS 

and  sizzling  similar  to  that  produced  by  a  piece  of  red- 
hot  iron  in  cold  water.  Xhere  is  also  a  dense  cloud  of 
so-called  steam  given  off.  This  bubbling  is  due  to  the 
action  of  the  acid  on  the  cyanide,  and  the  so-called 
steam  is  the  gas  being  produced.  The  result  of  this 
chemical  action  is  the  production  of  hydrocyanic  acid 
gas  (HCN),  known  in  the  liquid  form  as  prussic  acid, 
according  to  the  following  equation  :  2KCN  +  H2SO4 
=  2  HCN  H-  K2SO4.  The  gas  has  an  odor  somewhat 
similar  to  that  of  peach  pits,  but  do  not  stick  your 
nose  over  a  vessel  in  a  house  or  under  a  tent  to  test  it. 
These  fumes,  if  inhaled,  would  prove  fatal,  and  thus 
the  necessity  of  great  care. 

The  vessel. — Various  kinds  of  vessels  can  be  used 
for  the  acid  and  water.  Usually  an  ordinary  earthen 
jar,  china  dish,  or  bowl  is  used.  In  some  cases  a 
wooden  pail  or  tub  can  be  used  to  good  advantage. 
As  a  rule,  earthenware  vessels  are  employed  in  orchard 
and  nursery  fumigation.  The  size  of  the  vessel  will 
depend  upon  the  amount  of  material  to  be  used  for 
generating  the  gas.  Sometimes  in  mills,  warehouses, 
elevators,  and  other  enclosures  large  jars  or  wooden 
pails  containing  from  two  to  three  gallons  are  necessary. 
Under  no  circumstances  should  tin  or  iron  vessels  of 
any  kind  be  used,  as  the  acid  would  quickly  corrode 
and  ruin  them.  For  small  boxes  a  china  bowl  or  tea- 
cup can  be  used. 

Residue  in  the  jar. — After  a  charge  of  gas  has  been 
liberated  there  will  be  a  residue  left  in  the  jar.  At 
first,  and  while  still  warm,  it  is  a  whitish  liquid,  with 
a  bluish  cast,  but  as  it  cools  it  becomes  thick  like  paste 


HOW   THE   GAS   IS   MADE  II 

and  crystalizes  when  cold.  It  is  easily  soluble  in 
water.  Immediately  after  the  room,  tent,  or  other 
inclosure  has  been  ventilated  the  desired  length  of  time 
the  contents  of  the  jar  should  be  emptied  on  a  manure 
pile,  in  a  hole  prepared  especially  for  that  purpose,  or 
under  the  tree  close  to  the  trunk.  As  the  acid  and 
potash  left  behind  are  both  excellent  fertilizers  they 
should  be  saved  by  composting  them  either  with 
manure  or  dirt.  The  residue  consists  of  sulphate  of 
potash,  sulphuric  acid,  and  water.  The  sulphuric  acid 
will  unite  with  lime  in  the  soil,  forming  gypsum. 
Never  pour  the  residue  in  an  exposed  place,  where  a 
person  would  be  liable  to  step  in  it,  or  where  a  tent 
can  be  dragged  through  it. 

No  dangerous  deposit  formed. — The  question  is 
often  asked  about  the  possibility  of  hydrocyanic  acid 
gas  forming  a  deposit  upon  any  of  the  substances  with 
which  it  might  be  brought  in  contact  in  its  ordinary 
use  as  a  fumigant,  either  in  greenhouses  or  in  buildings 
infested  by  indoor  insects.  Dr.  H.  W.  Wiley,  chemist 
of  the  United  States  Department  of  Agriculture, 
states  that  there  is  no  possibility  whatever  of  such  a 
contingency,  unless  the  gas  comes  in  contact  with  some 
alkaline  body,  such  as  soda  or  potash,  with  which  it 
would  form  a  salt.  The  soluble  cyanides  are  extremely 
poisonous,  and  if  this  gas  were  to  act  upon  lye,  or  any 
similar  alkaline  body,  a  certain  amount  of  cyanide 
would  be  produced.  In  a  dry  room,  in  the  absence  of 
alkaline  bodies,  there  could  not  be  any  possible  danger  of  a 
poisonous  body  being  formed. 


CHAPTER   III 
PHYSIOLOGICAL   EFFECTS   ON  PLANTS 

s  NOTED  in  a  previous  chapter,  early  experi- 
menters had  observed  the  burning  effects  of 
the  gas  upon  foliage  when  used  under  certain 
conditions  and  overcome  the  difficulty  by 
night  fumigation.  It  remained  for  Dr.  Albert  F.  Woods, 
now  Chief  of  the  Division  of  Vegetable  Physiology  and 
Pathology,  United  States  Department  of  Agriculture, 
and  an  assistant,  P.  H.  Dorsett,  to  solve  this  problem 
in  connection  with  certain  greenhouse  plants.  In  1 894 
they  began  a  series  of  experiments,  and  proved  con- 
clusively that  plants  are  less  injured  by  a  short  ex- 
posure to  a  relatively  large  amount  of  gas  than  by  a 
long  exposure  to  a  relatively  small  amount,  and  also 
that  a  stronger  dose  a  short  time  was  more  destructive 
to  the  insects  affecting  the  plant.  They  further  de- 
monstrated the  physiological  effect  of  the  gas  upon 
the  plants  by  subsequent  experiments.  They  summed 
up  the  resisting  power  of  the  plant  as  dependent  largely 
upon  the  open  and  closed  condition  of  the  breathing 
pores  of  the  leaf,  the  peculiarities  of  the  cell  contents, 
and  the  temperature  of  the  inclosure. 

I  found  the  same  variations  in  the  field,  where  we 
used  the  gas  largely  in  the  control  of  San  Jose  scale 
and  other  insects.  The  first  problem  taken  up  in  this 
connection  was  the  physiological  effect  of  the  gas 
upon  deciduous  trees  in  the  East.  The  conditions  in 

12 


PHYSIOLOGICAL  EFFECTS  ON   PLANTS  13 

Eastern  orchards  were  quite  different  from  those  in 
California.  With  our  experiments  we  did  not  begin 
with  the  deciduous  trees  until  the  function  of  the  foli- 
age had  been  performed,  namely,  late  in  the  fall,  just 
previous  to  the  heavy  frost.  These  experiments  were 
conducted  in  late  September  and  early  October.  It 
made  little  or  no  difference  to  us  whether  we  scorched 
or  burned  the  leaves;  our  main  point  was  to  determine 
what  effect  the  treatment  was  going  to  have  upon  the 
fruit  or  leaf  development  for  the  following  season. 

The  next  practical  application  of  the  gas  was  its 
use  for  the  fumigation  of  nursery  stock.  As  no  pre- 
cise experiments  had  been  conducted  in  the  Hast,  the 
writer  began  a  series  in  March,  1897,  upon  young 
apple,  peach,  nectarine,  plum,  and  pear  trees.  They 
varied  in  hight  from  four  to  five  feet,  were  thoroughly 
dormant,  and  badly  infested  with  the  San  Jose  scale. 
They  were  placed  in  a  room  4x7x7^  feet,  prepared 
for  the  purpose.  A  general,  miscellaneous  lot  were 
exposed  thirty  minutes  in  gas  generated  from  0.20 
gramme  of  cyanide  of  potassium  per  cubic  foot  of  air- 
space inclosed.  Another  lot  was  exposed  to  gas  from 
0.20  gramme  up,  through  the  series  formed  by  adding 
0.05  gramme  each  time,  until  0.50  gramme  was 
reached.  All  the  trees  of  these  lots  were  observed 
very  closely  for  two  years.  No  injury  was  noticed, 
and  not  a  living  scale  was  ever  detected  upon  them. 
The  cyanide  used  in  these  experiments  was  the  98-99 
per  cent,  pure,  while  that  used  at  first  in  the  California 
orchards  was  the  old  58  per  cent. ;  this  must  be  taken 
into  account  when  considering  the  effects  of  the  gas 
on  trees  and  amounts  of  chemicals  used. 


14  FUMIGATION   METHODS 

Orchard  experiments. — In  the  fall  of  1897  I  began, 
perhaps,  the  largest  serie^  of  experiments  ever  under- 
taken in  the  East  for  the  destruction  of  San  Jose  scale. 
The  orchard  chosen  was  a  nine-year-old  Bartlett  dwarf- 
pear  in  full  foliage.  Canvas  tents  were  used.  The 
trees  were  fumigated  at  all  hours  of  the  day  and  under 
varying  conditions  of  weather.  We  had  sunshine, 
cloudy  and  foggy  days,  rain,  sleet  and  snow,  windy 
and  calm  weather.  In  one  series,  September  29th,  with 
a  temperature  of  70°  F. ,  we  used  0.40  gramme  cya- 
nide per  cubic  foot  instead  of  0.20,  as  in  most  of  our 
experiments.  The  leaves  on  all  the  trees  were  very 
brown,  in  fact,  almost  black.  Within  five  minutes 
after  the  tents  were  removed  the  petioles  were  black 
almost  to  the  base  ;  the  leaves  fell  a  few  days  later. 
The  following  spring  the  leaves  came  out  as  normally 
as  on  any  other  trees  in  the  orchard  where  no  fumiga- 
tion occurred.  There  was  about  one-quarter  as  much 
fruit  on  these  trees,  however,  as  upon  those  that  had 
been  fumigated  with  the  normal  strength,  that  is,  0.20 
gramme.  Other  trees  were  treated  at  night  with  the 
same  double  dose,  at  a  temperature  of  58°  F.  The 
foliage,  the  first  week,  showed  no  injurious  effect 
whatever,  and  remained  just  as  green  as  on  trees  not 
fumigated.  The  eighth  day,  however,  the  leaves  be- 
gan dropping,  and  a  few  days  later  were  all  off.  The 
leaf  buds  came  out  the  following  spring,  but  the  fruit 
was  only  about  half  as  abundant  as  on  surrounding 
trees.  The  double  dose,  it  would  therefore  seem,  is 
injurious  at  least  to  the  fruit  buds  of  Bartlett  pear 
under  such  conditions. 

The  final  outcome  of  the  whole  series  of  experi- 


PHYSIOLOGIC AI,   EFFECTS   ON   PLANTS  15 

ments  showed  that  gas  was  most  injurious  to  foliage 
on  sunshiny  days  late  in  the  fall  between  9  A.M.  and 
4  P.M.  ;  that  the  dormant  leaf  and  fruit  buds  treated 
with  o.  20  gramme  cyanide  per  cubic  foot  were  not  in- 
jured ;  that  burned  leaves,  that  is,  those  injured  by 
the  gas,  fall  readily ;  that  trees  treated  in  the  morning 
before  9  o'clock  and  in  the  afternoon  after  4  o'clock, 
even  in  sunshine,  have  the  leaves  little  affected ;  that 
trees  treated  at  night  with  normal  doses  do  not  have 
the  foliage  hurt  at  all. 

On  March  18,  1898,  experiments  were  begun  upon 
plum  trees,  using  the  same  standard  dose,  just  as  the 
buds  were  unfolding,  and  observed  no  injurious  effects 
whatever.  June  3,  1898,  eight  young  plum  trees, 
from  8  to  10  feet  in  hight,  were  fumigated  with  o.  16 
gramme  cyanide.  The  exposure  varied  from  5  to  12^ 
minutes,  in  the  sun  at  80°  F.;  in  every  instance  all 
the  lice  were  killed  and  the  foliage  not  injured.  July 
8,  1898,  three  cherry  trees  were  fumigated  with  o.  16 
gramme  cyanide  from  5  to  10  minutes.  The  trees 
were  infested  with  the  cherry  slug.  A  five-minute 
exposure  did  not  injure  the  foliage  at  all,  but  did  not 
destroy  over  60  per  cent,  of  the  slugs;  on  the  other 
hand,  7^  to  10  minutes  destroyed  all  the  slugs,  but 
.severely  hurt  the  leaves.  June  13,  1898,  two  pear 
trees,  badly  blighted,  were  fumigated  with  0.20 
gramme  cyanide  per  cubic  foot,  for  6  and  10  minutes 
respectively.  We  could  see  no  bad  effects  on  the 
leaves  and  no  decrease  in  the  blight.  In  April,  1899, 
after  the  buds  had  begun  to  open,  some  experiments 
were  completed,  using  0.20  gramme  cyanide,  upon 
pear  trees.  The  former  tests  had  been  made  during 


1 6  FUMIGATION   METHODS 

the  fall,  midwinter,  and  early  spring,  and  now  we  took 
up  the  effect  of  the  gas  on  the  trees  in  late  spring  as 
the  buds  began  to  open? 

Work  upon  nursery  stock. — Experiments  were  also 
performed  the  spring  of  1899  upon  nursery  stock,  for 
the  purpose  of  determining  the  precise  effect  of  the 
gas  upon  young  trees  used  at  a  strength  greater  than 
0.25  gramme  cyanide  per  cubic  foot.  Owing  to  the 
fact  that  some  states  stipulate  by  law  that  trees  must 
be  fumigated,  it  became  absolutely  necessary  that  we 
know  definitely  the  effect  of  this  gas  upon  growing 
plants,  especially  dormant  trees.  No  recent  experi- 
ments have  been  recorded  along  this  line,  as  far  as  I 
know.  We  have  been  using  0.25  gramme  cyanide  in 
general  work,  and  I  recommend  that  strength  for  all 
nursery  stock  above  three  feet  in  hight. 

Apple  trees. — We  began  our  experiments  with  the 
stronger  doses  March  29,  1899.  The  apple  trees  were 
divided  into  twenty  different  lots  of  five  trees  each, 
leaving  five  for  a  check.  They  were  4  to  5  feet 
in  hight,  and  of  the  following  varieties  :  Ben  Davis, 
Northern  Spy,  L,imbertwig,  Wealthy,  Fall  Pippin, 
Oldenburg,  Stark,  Rome  Beauty,  Schockley,  and  York 
Imperial.  They  were  exposed  in  gas  one  hour,  and 
each  lot  was  fumigated  with  0.25,  0.30,  0.40,  0.45, 
and  so  on,  adding  0.05  to  each  one  until  we  reached 
i. oo,  then  skipped  from  i.oo  to  1.25,  1.35,  and  1.45 
grammes,  thus  completing  the  series.  The  trees  were 
labeled  and  planted,  and  were  under  observations  two 
seasons. 

The    outcome    of    these    experiments    is    as   fol- 


FIG.    I — YORK    IMPERIAL   APPLE    TREE,    FUMIGATED    WITH    SIX 
TIMES    NORMAL    STRENGTH    OF    GAS    AND    NOT    INJURED 


18 


FUMIGATION   METHODS 


lows  :  I  had  fully  expected  that  the  gas  would  badly 
injure  the  trees  above  0.75.  In  fact,  no  apple  trees 
were  injured  in  the  least,  even  when  exposed  to  1.45 
grammes,  or  about  six  times  the  normal  strength, 


FIG.   2 — OGON    PLUM    TREE,   FUMIGATED    WITH    THREE    TIMES 
NORMAL    DOSE 

excepting  one  variety,  Northern  Spy.  I  can  not  ex- 
plain why  this  was  more  susceptible  to  the  gas  in  this 
test  than  the  others,  as  it  is  naturally  a  hardy  tree, 
and  its  resisting  properties  should  be  as  great  as  Ben 
Davis  or  any  of  the  other  varieties  treated.  The 


PHYSIOLOGICAL   EFFECTS   ON   PLANTS 


condition  of  the  Spy  in  general  appearance  was  about 
the  same  as  the  others,  and  the  buds  had  just  begun  to 

swell.      The   injury,    evidently, 

was  not  due  to  the  gas,  as  sub- 
sequent tests  with  normal  doses 
showed  that  no  injury  to  North- 
ern Spy  resulted. 

Figure  i  shows  one  of  the  York 
Imperial  apple  trees  in  this  ex- 
periment, fumigated  an  hour  in 
gas  representing  nearly  six  times 
the  normal  strength.  The  photo- 
graph was  taken  July  31,  1899. 
The  growth  was  good  and  the 
tree  was  in  perfectly  normal  con- 
dition when  the  experiment  was 
closed. 

Plum  trees, — Twenty  plum 
trees  of  the  following  varieties 
were  fumigated  April  17  and 
1 8,  1899  :  Abundance,  General 
Hand,  Genii,  Lombard,  Ogon, 
Shipper's  Pride,  and  Spalding. 
The  trees  varied  in  hight  from 
2  to  4  feet.  Bach  lot  had  one 
hour's  exposure,  with  0.35,  0.45, 
0.55,  0.65,  0.75,  1.25,  1.35,  and 
1.45  grammes  of  cyanide.  The 
results  obtained  are  very  strik- 
ing ;  for  instance,  there  was  no  damage  whatever  to 
any  varieties  until  0.65  gramme  was  reached,  when  the 
Spalding  had  terminals  slightly  injured,  while  General 


FIG.  3 — OGON  PLUM 
TREE,  FUMIGATED 


20  FUMIGATION   METHODS 

Hand  was  not  hurt.  At  0.75  gramme  Ogon  had  ter- 
minals slightly  injured^  as  shown  in  Fig.  2,  while 
Spalding  was  killed  to  the  ground,  but  later  sent  out 
shoots  at  the  base.  At  i.oo  gramme  Ogon  was  again 
only  slightly  hurt,  while  Abundance  was  dead  to  the 
surface  of  the  ground.  From  i.oo  to  1.35  Ogon  was 
slightly  injured  on  the  terminals,  as  can  be  seen  in 
Fig.  3- 

The  general  conclusions  drawn  from  these  tests 
with  plum  are  (i)  that  no  injury  will  result  where 
normal  dose  is  used  for  one  hour  or  less  on  well- 
matured  trees  over  two  feet  in  hight,  and  (2)  that 
some  varieties  are  more  resistent  to  injury  from  over- 
doses of  gas  than  others. 

Peach  trees. — The  experiments  upon  peach  trees 
were  commenced  April  26,  1899,  after  the  buds  had 
begun  to  swell.  There  were  250  trees,  one-half  of 
which  were  first-grade  Peninsula  Yellow,  4  to  5  feet, 
while  the  others  were  very  small,  varying  from  i^ 
to  2  feet  high.  The  trees  were  divided  into  lots  of  five 
each,  and  both  grades  treated  from  0.25  to  1.45 
grammes  cyanide  per  cubic  foot,  0.05  gramme  being 
added  each  time.  In  every  instance  the  short  grade 
trees,  known  as  ' '  whips, ' '  were  killed  outright,  or  the 
tops  were  killed,  sending  out  few  feeble  shoots  near  the 
ground  later.  This  corresponded  to  results  obtained  in 
1898,  that  June-budded  peach  and  plum,  and  small  whip- 
like  trees  from  i^  to  2^  feet,  can  not  withstand  more 
than  o.  1 8  gramme  for  half  an  hour.  On  the  other 
hand,  with  large  trees  there  was  no  perceptible  injury 
from  0.25  gramme  up  to  0.50  gramme.  At  the  latter 
strength,  double  the  normal,  the  terminals  were  injured 


FIG.    4 — I'EACH    TREE,    FUMIGATED    WITH    NORMAL    DOSE 


22  FUMIGATION   METHODS 

slightly,  as  shown  in  Fig.  5,  while  a  tree  given  a 
normal  dose,  0.25  gramme,  is  seen  in  Fig.  4.  In  0.75 
gramme  the  top  was  killed  about  one-third  the  way 
down,  as  seen  in  Fig.  6.  The  engravings  are  self- 
explanatory,  and  show  the  deadening  effect  with  the 
varying  degrees  of  gas  from  the  top  downward.  From 
0.75  gramme  to  i.oo  gramme  it  was  variable.  In 
.some  instances  the  whole  top  was  killed.  From  i.oo 
gramme  up  to  the  highest  amount  used,  1.45  grammes, 
a  curious  fact  was  noticed.  In  almost  every  case  the 
injury  was  not  as  great  above  i.oo  gramme  as  below 
0.75  gramme.  In  1.35  and  even  1.45  the  trees  were 
only  slightly  injured  at  the  top,  as  seen  in  Fig.  7, 
resembling  the  effects  produced  where  0.50  gramme 
was  used 

June-buds,  grafts,  and  buds. — Young  peach  and 
plum  trees,  known  as  June-buds,  should  not  be  fumi- 
gated with  the  stronger  doses.  Tests  made  in  1 898  show 
that  nursery  stock  of  this  kind  will  not  withstand  the 
gas  when  generated  with  cyanide  above  o.  18  gramme 
per  cubic  foot.  Any  wood  not  well  matured  is  liable 
to  be  injured  if  a  greater  amount  of  cyanide  is  used. 
For  stock  of  this  character  o.  16  to  o.  18  gramme  cya- 
nide per  cubic  foot  is  recommended,  at  an  exposure  of 
one-half  hour  and  no  longer.  The  scale,  under  ordinary 
circumstances,  is  destroyed  wrhen  fumigated  with  0.12 
to  o.i 4  gramme  cyanide.  The  0.15  to  o.  18  formula 
can  be  used  with  perfect  safety  on  buds,  grafts,  and 
scions. 

Roses  and  other  siipplies. — In  fumigating  roses  and 
other  materials  handled  by  florists  the  cyanide  should 


24  FUMIGATION  METHODS 

be  reduced  to  o.  10  to  o.  15  gramme  cyanide.  As  a  rule, 
it  is  not  desirable  to  fumigate  such  plants  as  cedars, 
pines,  etc. 

Seeds  of  various  kinds  can  be  fumigated  in  nor- 
mal amounts  of  gas  with  perfect  safety,  the  varying 
physiological  effects  depending  upon  the  condition  of 
the  grain  or  seed,  whether  dry  or  moist,  upon  the 
amount  of  gas  used,  the  length  of  time  exposed,  and 
the  atmosphere  in  which  it  is  confined,  whether  dry, 
damp,  or  saturated.  This  is  treated  more  fully  later 
in  another  chapter. 

Low-growing  plants  may  be  fumigated  for  the  de- 
struction of  the  root  aphis,  leaf-rollers,  and  other 
insects,  but  the  work  must  be  done  with  the  same  care 
as  for  other  plants.  Lettuce,  cucumber,  and  canta- 
loups are  very  easily  injured  if  the  plants  are  damp, 
even  with  small  amounts  of  gas.  In  tests  made  by  Pro- 
fessor K.  D.  Sanderson,  of  the  Delaware  Agricultural 
Experiment  Station,  upon  young  cantaloups  after  a 
shower,  he  found  the  plants  were  injured  in  0.40 
gramme  of  cyanide  per  cubic  foot  for  ten  minutes.  Pre- 
liminary tests  should  be  made  with  o.  10  to  0.20  gramme 
for  ten  to  twenty  minutes  before  an  entire  house  is  ex- 
posed. Professor  Sanderson  has  shown  also  that  straw- 
berry plants  freshly  dug  and  fumigated  in  a  box  will 
withstand  o.  20  gramme  cyanide  fifteen  minutes.  His 
tests  show  that  this  strength  will  kill  the  aphids  on  the 
roots  and  not  injure  the  plants.  Other  details  are  given 
in  a  later  chapter  on  this  topic. 


CHAPTER  IV 
EFFECTS   ON   ANIMAL   LIFE 


O""lwiNG  to  the  very  deadly  nature  of  hydrocy- 
^^  anic  acid  gas  if  inhaled  by  animals,  the 
following  instances  are  given  as  a  warning 
to  those  who  may  handle  this  material. 

A  fortunate  accident  happened  in  a  fumigating 
house  which  should  be  a  signal  warning  to  those  who 
may  use  this  gas.  The  house  had  been  filled  with 
Norway  maple  trees,  and  after  the  usual  length  of 
time  the  doors  were  thrown  open.  At  the  expiration 
of  seven  minutes  a  negro  laborer,  who  had  been  re- 
peatedly warned  not  to  enter  the  room  under  ten 
minutes,  went  in  and  began  handing  out  the  trees  to 
another  negro  standing  at  the  door.  He  handed  out 
two  bundles,  and  while  stooping  for  the  third  fell 
headlong  on  the  floor.  He  was  immediately  pulled 
out,  laid  on  his  back  in  the  open  air,  recovered  con- 
sciousness in  about  fifteen  minutes,  and  was  seemingly 
as  well  as  ever  in  half  an  hour.  When  asked  what 
had  happened  and  how  he  felt,  he  replied,  "  De  I/ord 
only  knows  dat  stuff  am  a  powf ul  axfitter  ! ' ' 

Another  peculiar  accident  happened  during  our 
experimental  operations  at  Mr.  Emory's.  Our  cyanide 
having  been  shipped  to  us  in  lumps  too  large  for  use, 
we  found  it  necessary  to  break  it  up  in  smaller  pieces. 
In  order  to  do  this  and  keep  it  from  flying,  we  covered 
it  with  an  old  fertilizer  bag.  After  the  cyanide  had 

25 


26  FUMIGATION  METHODS 

been  removed  from  the  bag  and  the  smaller  particles 
shaken  out,  the  bag  was  again  shaken  out  the  window 
to  free  it  of  any  particle's  that  may  have  remained. 
As  a  result,  a  few  small  pieces,  not  larger  than  a  pin's 
head,  were  shaken  on  the  ground.  Two  fine,  large 
chickens,  especially  prized  by  their  keeper,  roaming 
about,  picked  up  some  of  the  cyanide,  and  in  less  time 
than  it  takes  to  write  this  account  they  were  on  their 
backs.  One  died  in  a  very  few  moments,  while  the 
other  recovered,  evidently  not  having  gotten  so  much. 

Professor  Woods  tells  me  that  a  favorite  cat,  asleep 
under  a  bench  in  one  of  the  greenhouses  he  fumigated, 
was  killed  without  being  awakened.  A  dog  was 
placed  in  one  of  our  fumigating  houses  to  test  the 
effect  of  the  gas  upon  animal  life,  after  the  room  had 
been  opened  and  aired  for  seven  minutes,  and  again 
closed.  The  animal  was  removed  after  five  minutes' 
exposure  in  an  unconscious  condition,  but  recovered 
in  half  an  hour. 

Frequently  the  writer  has  placed  toads,  frogs, 
snakes,  pigeons,  sparrows,  rats,  mice,  dogs,  and  cats 
in  some  remote  corner  in  buildings  to  test  the  thor- 
oughness of  the  diffusion  of  the  gas.  In  every  case 
the  animal  was  dead  when  removed.  Many  instances 
could  be  cited,  but  this  will  suffice  our  purpose  in 
warning  those  who  use  cyanide  or  hydrocyanic  acid 
gas  that  they  are  exceedingly  dangerous  substances 
and  must  be  handled  carefully. 


CHAPTER  V 
APPARATUS    FOR    USE    IN    ORCHARDS 

T"!HE  equipment  necessary  for  orchard  fumigation 
depends  largely  upon  the  kind  of  trees  to  be 
treated  and  the  location  of  the  orchard.  In 
California  the  sheet  tent  is  in  general  use. 
Another  form,  known  as  the  bell  tent,  is  also  quite 
commonly  used  in  California  orchards.  Of  the  earliest 
apparatus  used,  the  Wolf  skill  fumigator  was  a  good 
type.  It  is  a  bell  tent  manipulated  by  a  derrick 
mounted  on  a  wagon.  It  has  an  arm  on  each  side 
extending  over  the  top  of  the  trees  when  driven  be- 
tween the  rows.  This  form  of  tent  is  lifted  up  by 
means  of  a  rope  attached  to  the  top  and  extending  to 
a  loop  at  the  end  of  the  arm  or  derrick,  through  which 
the  tent  is  drawn  as  it  is  removed  from  the  tree.  This 
form  of  tent  is  shown  in  Fig.  8. 

Another  form,  known  as  the  Titus  fumigator 
(Fig.  9),  consisted  of  a  smaller  tent,  supported  by  a 
square  frame  braced  at  each  corner  and  mounted  on 
wheels  with  a  piece  across  the  top,  on  which  the  tent 
could  be  wound  in  removing  it  from  the  tree.  Still 
another  form,  known  as  the  Culver  fumigator  (Fig. 
10),  consisted  of  two  light  frames,  half-bell  shaped, 
covered  with  cloth.  It  formed  a  complete  tent  when 
closed  together  around  the  tree.  This  form  of  fumi- 
gator was  simplified  later  and  the  cloth  allowed  to  rest 
on  the  sides  of  the  tree.  The  Culver  outfit,  in  con- 

27 


28  FUMIGATION  METHODS 

nection  with  the  Morse  f umigator,  is  shown  in  Fig.  1 1 . 
All  the  earlier  forms  q£  fumigators  were  provided 
with  generators  and  blowers.  They  have  all  been 
superseded  by  different  forms  of  tents  better  adapted 
for  orchard  work. 

To  meet  the  general  conditions  in  the  East  and 
other  places,  I  have  perfected  still  another  form,  which 
has  been  called  the  Kmory  fumigator,  and  is  shown 
in  Figs.  32  to  35.  On  large  orchard  trees  the  sheet 
tents  are  better  adapted  for  general  work  than  the  box 
tents.  The  Emory  fumigator  is  especially  adapted  for 
trees  under  ten  feet  in  hight. 

The  canvas  or  sheet  tent. — The  octagonal  form 
known  as  the  sheet  tent  has  been  used  largely  in 
California  and  by  the  United  States  Department  of 
Agriculture.  The  size  of  these  tents  depends  upon 
the  size  of  the  trees  to  be  fumigated.  Sheets  from 
twenty-five  to  forty  feet  and  over  in  diameter  are  in 
common  use.  One  tent  used  in  my  experiments  was 
forty-five  feet  in  diameter  and  was  used  only  on  large 
trees.  Another  canvas  tent,  made  in  several  sections 
with  a  square  top  and  base,  designed  by  R.  S.  Emory, 
is  shown  in  Fig.  12.  These  tents  vary  in  size  to  meet 
the  requirements  under  different  conditions  in  various 
orchards.  A  very  convenient  size  of  canvas-box  tent 
is  fifteen  feet  square  at  the  bottom,  ten  feet  square  at 
the  top,  and  fifteen  feet  high.  Occasionally  tents  of 
this  same  design  of  much  smaller  dimensions  are  used, 
but  they  are  not  generally  recommended. 

Construction  of  tent. — All  tents  now  in  general  use 
are  usually  made  of  eight-ounce  cotton  duck,  such  as 


FIG.    8 — THE    WOLFSKILL    FUMIGATOR 


FUMIGATION   METHODS 


is  used  by  the  Army  and  Navy  for  tents  and  light  sails. 
With  little  care  any  awning  or  tent  maker  can  cut  the 
sheet  tents  so  there  is  practically  no  waste  in  material. 
They  are  usually  cut  and  made  into  quadrants  and  then 
put  together.  The  center  in  the  large  tents  is  usually 


FIG.    9 — THE    TITUS    FUMIGATOR 

double  for  a  space  of  about  two  feet  in  diameter,  as 
there  is  considerable  strain  upon  the  material  at  this 
point.  A  half-inch  or  five-eighths  inch  rope  should  be 
hemmed  in  around  the  edges. 

The  cost  varies  according  to  the  size,  and  the 
expense  of  oiling  must  be  added.  All  tents  should  be 
thoroughly  oiled  by  painting  them  with  boiled  linseed 
oil.  Usually  one  or  two  coats  will  be  sufficient.  The 


APPARATUS   FOR   USE   IN   ORCHARDS  3! 

following   quotations,   including  oiling,  were  secured 
from  a  Baltimore,  Md.,  tent-maker  : 

Sheet  tent,  with  square  top  and  base,    4x    5x    2  ft.  .     .  $2.00 
"       "        "        7  x  10  x   4  "    .     .     7.00 

"         "         "         "          "       "        "       10x15x15"    .     .  12.50 

"         "     octagonal  form,  25  ft.  in  diameter     ....   18.00 

"          "  "       30     "  ....   25.00 

"       45     "  "  ....  42.00 


FIG.    10 — THE    CULVER    FUMIGATOR 


In  constructing  tents  the  cloth  is  lapped  and  doubly 
sewed  in  the  same  manner  as  for  tents  or  sails.  The 
edge  can  be  either  hemmed  or  bound  with  rope.  If 
permanent  rings  for  handling  are  attached  the  tent 
may  need  reinforcement.  The  general  details  of  the 


32  FUMIGATION   METHODS 

construction  depend  somewhat  upon  the  persons  doing 

the  work. 

• 

Oiling  and  painting. — In  order  to  make  a  tent 
gas-tight  it  is  necessary  to  cover  it  with  oil,  paint, 
or  other  material.  Several  methods  are  in  general 


FIG.    II — CULVER    TENT   AND    MORSE    FUMIGATOR 


use  for  this  purpose,  all  of  which  have  been  used 
with  considerable  satisfaction.  A  free  application 
of  boiled  linseed  oil  is,  perhaps,  the  method  most 
commonly  used.  After  the  tent  is  thoroughly  satu- 
rated with  oil  it  should  be  spread  out  or  tacked  to  the 
side  of  a  building  where  it  can  dry.  Care  must  be 


APPARATUS   FOR   USE   IN   ORCHARDS  33 

taken  that  the  oil  is  thoroughly  dry,  otherwise  it  has 
a  great  tendency  to  generate  heat  if  the  tent  is  folded 
and  left  for  any  length  of  time.  The  cloth  burns  or 


FIG.    12 — CANVAS    TENT    WITH    SQUARE   TOP   AND   BASE 

chars  and  is  ruined.  On  the  other  hand,  if  the  tent  is 
thoroughly  dry  after  oiling,  it  is  easily  handled  and  can 
be  folded  with  per  feel:  safety. 

In  some  cases  paint  is  used.     It  is  applied  with  a 
brush  in  the  same  manner  as  the  oil  and  penetrates  the 


34  FUMIGATION   METHODS 

cloth,  filling  the  fiber  in  the  same  way,  making  it 
when  dried  thoroughly  gas-proof.  As  soon  as  the 
paint  is  dry  the  sheet  is  covered  with  another  coat  of 
rather  flexible  paint.  When  dry  this  coating  makes  a 
perfectly  tight  tent,  with  a  smooth  surface  and  quite 
as  flexible  and  easily  handled  as  the  oiled  tent. 

Still  another  method  is  used  in  some  places.  A 
decoclion  is  made  by  filling  a  barrel  two-thirds  full  of 
chopped  stems  and  leaves  of  the  common  prickly  pear 
cactus  {Opuntia  engelmani).  Afterward  the  barrel  is 
filled  with  cold  water  and  is  allowed  to  stand  twenty- 
four  hours.  The  liquid  is  then  drawn  off  and  ready  for 
use  by  adding  a  pigment,  like  yellow  ochre  or  Venitian 
red.  Sometimes  a  small  quantity  of  glue  is  added. 
To  prevent  molding  when  not  in  use  and  folded,  a  small 
quantity  of  tannin  solution  is  added  to  the  mixture. 
This  solution  can  be  applied  to  the  tents  with  a  brush, 
but  where  a  sufficient  quantity  is  on  hand  it  is  better 
to  soak  the  sheets  over  night  in  a  vessel  containing  the 
mixture.  They  should  then  be  taken  out  of  the 
material,  thoroughly  drained,  and  spread  out  to  dry. 
This  method,  however,  is  not  generally  used,  but  has 
given  very  satisfactory  results,  as  the  cloth  is  not 
stiffened,  and  is  made  quite  flexible  and  easily  handled. 


CHAPTER  VI 
BELL   AND   HOOP  TENTS 

T|HE  tents  known  as  bell  tents  are  cylindrical  in 
shape,  with  the  top  rounded  over  like  a  dome. 
They  are  used  in  connection  with  a  derrick, 
by  means  of  which  they  are  placed  upon  and 
lifted  from  trees;  the  derrick  also  supports  the  weight  of 
the  tent  while  it  is  upon  the  tree.  The  bell  tent  was  one 
of  the  original  forms  of  tents,  and  while  mostly  sup- 
planted by  other  styles,  is  still  used  to  a  considerable 
extent,  especially  for  very  large  trees.  It  is  the  only 
form  of  tent  now  in  use  where  the  whole  weight  of  the 
tent  is  not  carried  by  the  tree,  and  many  favor  it  for 
this  reason.* 

The  derrick  used  with  the  bell  tents  at  the  present 
time  is  that  used  with  the  Preble  fumigator,  or  some 
modification  of  it.  This  is  shown  in  Fig.  13.  It  con- 
sists of  a  wagon,  which  supports  a  mast  considerably 
higher  than  the  trees  to  be  fumigated,  and  is  braced  at 
the  bottom  with  stays  that  hold  it  rigidly  in  place. 
Across  the  top  of  the  mast  a  yard  is  fastened  and 
braced  with  trusses  extending  from  the  mast.  The 
length  of  the  yard  is  about  a  third  longer  than  the 
distance  between  the  rows  of  trees.  Near  each  end  of 


*  This  description  is  taken  from  the  excellent  bulletin 
(No.  122)  by  Prof.  C.  W.  Woodworth,  of  the  California 
Experiment  Station. 

35 


36  FUMIGATION   METHODS 

the  yard  are  placed  cross-bars,  as  shown  in  the  illus- 
tration. The  arrangement  of  the  ropes  can  be  under- 
stood from  a  study  of  the  figure. 

The  heaviest  rope  is  attached  to  the  top  of  the  tent 
with  double  pulleys.     Along  the  lower  edge,  on  the 


FIG.    13 — THE    PREBLE    FUMIGATOR,    AS    USED    IN 
CALIFORNIA    ORCHARDS 


four  sides  of  the  tent,  are  fastened  boards,  generally  of 
ordinary  six-inch  fencing,  which  are  called  trail  boards, 
and  from  the  center  of  each  of  these  the  trail  ropes 
pass  upward  and  over  pulleys  attached  to  the  yard  and 
ends  of  the  cross-bars.  All  these  ropes  follow  the 
yard  till  near  the  mast,  then  passing  again  over  pul- 
leys, they  go  down  to  the  bed  of  the  wagon  and  are 
fastened  over  belaying-pins.  The  trail  ropes  pass 


AND    HOOP   TENTS 


37 


through  thimbles  along  the  side  of  the  tent  as  well  as 
through  the  pulley  at  the  center  of  the  trail,  so  that 
when  the  latter  is  drawn  up  to  the  yard,  or  cross-bars, 
the  sides  of  the  tent  are  gathered  in  three  or  four 
places  and  raised  almost  as  high.  The  only  other 
ropes  are  the  guide  lines  attached  to  the  center  of  the 


FIG.    14 — RAISING    SMALL    HOOP    TENT 

trails  and  hanging   free.     They  are   of   such  length 
as  to  reach  the  ground  when  the  tent  is  elevated. 

The  manipulation  of  these  tents  can  be  readily 
understood  from  a  study  of  the  engraving.  While 
the  tree  is  being  fumigated  the  tent  is  usually  allowed 
to  rest  partly  on  the  tree  and  not  drawn  up  to  the 
yard,  as  shown  in  the  illustration.  Two  persons  can 
handle  the  apparatus,  but  three  or  four  greatly  facili- 
tate the  work.  The  procedure  in  changing  the  tent  is 


38  FUMIGATION  METHODS 

as  follows :  Supposing  that  both  tents  are  upon  the 
trees  and  the  time  has  Arrived  to  make  the  change, 
the  first  operation  is  to  pull  on  the  main  rope  attached 
to  the  center  of  the  tent  and  raise  this  as  far  as  it  will 
go  easily,  and  then  fasten  the  rope  again  to  the  belay- 
ing-pin.  If  short-handed,  one  tent  is  raised  at  a  time, 


FIG.    15 — SMALL    HOOP   TENT   ALMOST   IN   POSITION 

but  with  plenty  of  help  both  go  up  at  the  same  time. 
The  trail  ropes  are  next  taken  in  hand  and  pulled  all 
together,  and  if  this  becomes  difficult,  two  (or  even 
one  at  a  time)  are  pulled  until  the  tent  on  all  sides  is 
pulled  up  to  the  yard  and  cross-bars. 

While  this  is  going  on,  one  person  (or  perhaps 
more)  is  kept  busy  seeing  that  the  tent  is  clearing  the 
tree  properly.  His  first  business  is  to  see  that  the 


AND   HOOP   TENTS  39 

edge  with  the  trail  boards  is  not  caught  inside  of  the 
tent;  it  should  slip  up  around  outside  of  it.  L,ater  he 
will  be  occupied  with  making  the  tent  slip  off  the  pro- 
jecling  branches.  He  can  generally  do  this  by  pulling 
on  the  guide  lines,  but  on  very  large  trees  he  may  find 
a  light  ladder  necessary.  The  removal  of  the  tent 


FIG.  l6 — SMALL  HOOP  TENT  READY  FOR  CHEMICALS 

would  be  comparatively  easy  but  for  the  work  at  the 
ropes.  After  all  the  ropes  are  pulled  tight,  including 
the  main  rope,  and  both  tents  are  against  the  yard,  the 
apparatus  is  ready  to  shift  to  the  next  row.  The 
wagon  may  be  pulled  along  by  hand,  or  by  a  horse 
hitched  to  the  end  of  the  tongue.  If  the  ground  is  a 
little  uneven,  the  apparatus  can  be  kept  from  tipping 
over  by  steadying  it  with  the  guide  lines.  Arriving 


40  FUMIGATION   METHODS 

at  the  proper  position  between  the  next  two  trees,  the 
first  thing  is  to  arrange  the  guide  lines  in  their  places 
around  the  tree.  The  trail  ropes  are  now  released  and 
the  tent  is  allowed  to  slowly  descend  upon  the  tree. 
While  this  is  taking  place,  one  or  more  are  busy  with 


FIG.    17 — LIFTING    LARGE    HOOP    TENT    FROM    GROUND 


the  guide  lines,  pulling  the  trail  boards  this  or  that 
way  as  may  be  necessary  to  clear  the  branches. 

If  a  branch  is  particularly  spreading  it  may  be 
necessary  to  use  a  ladder,  forcing  it  within  the  tent  by 
hand.  Should  the  trees  be  very  large  the  branches 
will  extend  over  the  wagon,  causing  much  trouble  in 
pulling  the  tent  down  on  that  side.  With  a  small, 
symmetrically  shaped  tree  the  tent  can  be  lowered  rap- 
idly into  place  without  any  trouble  whatever.  After 


BEU,   AND   HOOP   TENTS  41 

the  trail  ropes  are  all  played  out,  the  main  rope  is 
loosened  and  the  tent  allowed  to  settle  to  the  position 
desired,  and  fastened  there.  There  yet  remains  the 
job  of  seeing  that  the  tent  is  tight  to  the  ground  on  all 
sides.  The  trail  boards  are  made  to  lie  on  the  part  of 
the  tent  that  is  on  the  ground,  and  earth  is  thrown  on 


FIG.     IS — ADJUSTING    LARGE    HOOP   TENT 

any  part  of  the  edge  of  the  tent  that  does  not  lie  down 
well.  When  both  tents  are  thus  in  position  they  are 
ready  for  the  man  who  charges  the  generator. 

The  hoop  tent. — The  form  most  used  in  California  is 
the  hoop  tent,  which  is  a  development  from  the  bell 
tent,  and  is  of  the  same  general  shape.  The  hoop  was 
first  used  as  a  means  of  keeping  the  mouth  of  the  bell 
tent  open,  but  it  was  soon  discarded  in  favor  of  the 


42  FUMIGATION   METHODS 

trail  boards.  It  was,  however,  discovered  that  for 
rather  small-sized  tents  yie  hoop  afforded  a  better 
means  of  handling  than  did  the  derrick. 

The  hoop  tents  now  in  use  range  from  eight  to 
fourteen  feet  in  diameter.  They  are  made  in  the  same 
way  as  a  bell  tent,  omitting,  however,  the  arrange- 
ments for  suspending  them,  and  possessing,  instead,  a 
series  of  cloth  loops  for  attaching  the  hoop,  as  is  shown 
in  the  engraving. 

The  hoop  is  usually  made  of  three-quarter-inch  gas- 
pipe;  half-inch  pipe  will  do  for  the  smaller  sizes,  but  it 
is  too  weak  for  hoops  above  ten  feet  in  diameter,  as  it 
bends  too  easily  and  soon  becomes  very  crooked.  To 
make  the  hoop,  pipe  is  coupled  together  until  the  proper 
length  is  reached,  according  to  the  size  desired,  and 
then  bent  into  shape.  The  union  is  then  made  by  in- 
serting into  the  ends  a  piece  of  iron  rod  a  foot  or  less 
in  length  and  just  small  enough  to  enter  the  pipe. 
Holes  are  now  drilled  through  the  pipe  and  rod,  and 
rivets  are  inserted,  thus  making  the  joint  fast.  A 
coupling  with  right  and  left  hand  threads  might  be 
used  instead  of  the  rod  and  rivets. 

The  manipulation  of  a  hoop  tent  varies  according 
to  its  size.  When  the  diameter  of  a  tent  is  not  much 
greater  than  the  distance  between  the  nearest  branches 
of  adjacent  trees,  the  procedure  is  that  illustrated  in 
Figs.  14-16. 

To  move  such  a  tent  from  one  tree  to  the  next,  two 
men  place  themselves  on  opposite  sides  of  it,  grasp  the 
hoop,  and  raise  the  side  which  is  opposite  the  tree  to 
which  they  intend  to  move  it ;  they  step  sidewise, 
dragging  the  side  that  is  on  the  ground  closer  to  the 


AND    HOOP   TENTS  43 

trunk.  The  men,  still  holding  the  hoop  as  they  first 
grasped  it,  continue  to  raise  the  free  side  until  it 
passes  over  the  top  of  the  tree,  when  it  is  allowed 
to  fall  to  the  ground  between  the  two  trees.  In 
falling,  the  hoop  naturally  moves  away  from  the  tree 
from  which  it  came,  so  that  the  cloth  falls  over  the 


FIG.    19— LIFTING   TENT    AFTER    FUMIGATION 

edge  of  the  hoop.  If  this  does  not  occur,  the  tent 
is  pulled  into  that  position  in  order  that,  when 
the  hoop  is  raised,  the  center  of  the  tent  will  be 
brought  at  once  to  about  the  center  of  the  top  of  the 
tree. 

The  men  now  grasp  the  hoop  again,  as  before, 
carry  it  toward  the  tree  and  lift  up  the  further  edge, 
then  with  one  movement  throw  it  over  the  tree.  Often 
it  will  go  clear  to  the  ground  and  needs  no  further 


44 


FUMIGATION    METHODS 


attention.  The  cloth  which  extends  beyond  the  hoops 
forms  a  sufficiently  tight  contact  with  the  ground  if 
the  latter  is  ordinarily  level. 

The  manipulation  of  the  large  hoop  tents  differs 
from   that  above   described,   from   the  fact  that    the 


FIG.    2O — COVERING    TREE    WITIP  LARGE    HOOP    TENT 

proximity  of  the  trees  makes  it  impracticable  to  lay  the 
tent  on  the  ground.  The  procedure  in  this  case  is 
indicated  by  Figs.  17-20  and  in  the  accompanying 
diagram,  Fig.  21. 

It  is  better  to  have  three  men  handle  these  tents, 
though  two  can  do  it.  When  working  three,  two 
take  hold  in  the  same  way  as  described  above  for  the 
small  hoop  tents,  and  the  third  pulls  on  the  side 
that  is  raised.  The  latter  then  catches  the  hoop  with 
a  fork  at  the  end  of  a  pole,  and  as  the  others  lift 


OBELI*  AND   HOOP   TENTS  45 

he  assists  by  pushing.     This   is  shown  in  Figs.    19 
and  20. 

When  the  hoop  has  taken  about  the  position  shown 
at  B,  in  Fig.  21,  or  a  little  past  that  point,  the  two 
men  holding  the  sides  of  the  tent  carry  it  to  the  next 
tree  to  the  position  C,  and  then  without  pausing,  and 
while  the  tent  is  full  of  air  and  streaming  out  behind 
with  the  aid  of  momentum  acquired,  the  upper  edge 


FIG.    21 — DIAGRAM    ILLUSTRATING    METHOD    OF    SHIFTING 
LARGE    HOOP    TENT.       (AFTER    WOODWORTH) 

of  the  hoop  is  forced  over  the  top  of  the  tree  and  down 
on  the  other  side.  Generally  it  is  possible  to  throw 
the  hoop  into  the  position  D,  when  it  can  readily  be 
pulled  down  to  the  ground. 

If  there  is  any  trouble  in  pulling  the  cloth  over,  the 
third  man,  having  tossed  his  pole  to  the  next  tent,  goes 
around  to  the  near  side  of  the  tent  just  moved,  and  as 
the  others  pull  on  the  far  side,  shakes  the  cloth  of  the 
tent  away  from  the  tree,  thus  relieving  some  of  the  fric- 
tion. The  weight  of  the  hoop  of  these  large  tents  greatly 
helps  in  the  process  of  slipping  the  cloth  over  the  tree, 


46  FUMIGATION   METHODS 

the  most  energy  being  required  in  removing  the  tent. 
The  large  tents  are  ino^fed  quite  as  rapidly  as  are  the 
smaller  ones.  It  will  be  noticed  that  the  cloth  is 
turned  inside  out  with  each  change  in  the  case  of  the 
larger  tents,  but  with  the  smaller  ones  the  same  side 
of  the  cloth  is  always  next  to  the  tree. 


CHAPTER  VII 


CONSTRUCTION    AND    MANAGEMENT    OF   SHEET 
TENTS 

T~!HERE  are   many   methods   used   for    handling 
sheet  tents  in  orchards.     A  single  pole,  such 
as  shown  in  Fig.   24,  is  very  useful.     The 
pole  is  known  as  a  "  lifter, ' '  and  consists  of 
an  eighteen-foot  yellow  pine  sapling,  thoroughly  sea- 


/!\\ 

/       4      \«.         * 

/  ft    \  N! 

"  %        - 


FIG.  23 — MANIPULATING  SHEET  TENTS  WITH  A  SINGLE  POLE 
(AFTER  WOODWORTH) 

soned,  such  as  is  used  on  ordinary  sail-boats.  It 
should  be  about  four  inches  in  diameter  at  the  base, 
tapering  to  about  three  inches  at  the  top.  Such  a  pole 
is  strong,  light,  and  very  durable.  A  piece  of  3  x  4 
inch  scantling  is  nailed  at  the  base  and  braced,  as 
shown  in  the  illustration.  A  small  block  pulley, 
large  enough  to  carry  a  five-eighths  inch  rope,  is 
screwed  near  the  top  of  the  lifter.  Forty  to  fifty  feet 
48 


FIG.    24 — METHOD    OF    COVERING    A    TREE    WHEN    A    SINGLE 
POLE    IS    USED 


50  FUMIGATION   METHODS 

of  half  or  five-eighths  inch  rope  will  be  needed  in  the 
pulley.  This  is  called  the  "pulley  rope."  A  cleat 
should  be  attached  to  tne  side  of  the  lifter  about  five 
feet  from  the  ground.  The  pulley  rope  is  attached  to 
this  when  the  tent  is  hoisted.  Another  piece  of  rope, 
twenty-five  to  thirty  feet  in  length,  should  be  tied  near 


FIG.    25 — REMOVING    SHEET    TENT   BY    MEANS    OF    POLE   AND 
HELPERS 

the  top  of  the  lifter  above  the  pulley.  This  is  called 
the  "stay  rope."  The  lifter  is  kept  in  place  by 
means  of  the  stay  rope  by  tying  it  to  an  adjacent  tree, 
as  illustrated. 

Various  other  appliances  will  be  found  helpful. 
Usually  the  conditions  will  suggest  some  improvement 
whereby  the  tents  can  be  handled  more  easily.  A 
hand  pole,  such  as  is  shown  in  Fig.  25,  can  be  used  to 
good  advantage  in  tenting  and  untenting  a  tree.  This 


52  FUMIGATION   METHODS 

is  known  as  the  ' '  helper, ' '  by  means  of  which  the 
weight  of  the  tent  can  be  kept  from  the  tender 
branches  of  the  tree.  The  helper  shown  in  the  illus- 
tration gives  a  good  idea  of  the  construction  and  its 
method  of  use.  In  this  particular  case  the  tent  is 
being  removed  from  the  tree  which  has  just  been 
fumigated. 

To  tent  a  tree  where  a  single  lifter  is  used,  it  should 
be  set  at  an  angle  of  about  sixty  degrees  and  the  stay 
rope  fastened  to  an  adjoining  tree,  thus  holding  it  in 
place,  as  shown  in  Fig.  23.  One  end  of  the  pulley  rope 
is  then  passed  around  the  tree  and  tied  to  the  tent  lying 
on  the  ground  on  the  opposite  side.  The  operator  at  the 
lifter  then  draws  the  tent  to  the  pulley  and  fastens  the 
rope.  He  then  steps  back  a  few  feet,  and,  taking  the 
stay  rope,  pulls  the  lifter  to\vard  himself  until  the 
center  of  the  tent  is  about  over  the  top  of  the  tree,  as 
shown  in  Fig.  24.  In  the  mean  time  the  other  assist- 
ant brings  the  sides  of  the  tent  around  toward  the 
lifter.  The  operator  takes  one  side  while  the  assistant 
holds  the  other,  as  shown  in  the  illustration.  When 
the  lifter  is  at  the  proper  angle  to  bring  the  center  of  the 
tent  over  the  top  of  the  tree,  one  side  of  the  tent  is 
then  passed  to  the  assistant  between  the  lifter  and  the 
tree,  while  the  operator  loosens  his  pulley  rope  and  lets 
the  tent  fall  in  position  over  the  tree.  The  assistant 
unties  the  stay  and  pulley  ropes  and  carries  the  lifter  to 
the  next  tree,  while  the  operator  banks  the  tent  or  folds, 
the  cloth  around  the  base  of  the  tree.  Often  a  few 
shovelfuls  of  earth  are  necessary  to  hold  the  bottom  of 
the  tent  in  place,  if  there  is  not  a  sufficient  amount  of 
canvas  to  fall  on  the  ground.  If  the  wind  is  blowing 


54  FUMIGATION  METHODS 

and  the  tent  is  a  little  slack  a  few  pieces  of  stone  or 
chunks  of  wood  may  be  required  to  hold  it  down. 

When  the  trees  are  uniform  in  size  as  many  rows 
are  taken  as  there  are  tents  in  use.  The  sheet  tents 
are  then  transferred  from  tree  to  tree  by  simply  revers- 
ing them  over  and  over  again.  The  method  varies 
from  the  foregoing  only  in  the  fact  that  the  pulley 
rope  is  carried  around  the  side  opposite  the  lifter  and 
fastened  to  the  bottom  of  the  tent  covering  the  trees. 
The  lifter  is  also  set  at  a  more  acute  angle.  The  can- 
vas tents  with  square  tops,  however,  can  not  be  re- 
versed in  this  manner.  In  such  cases  they  are  taken 
from  the  tree,  lowered,  and  again  hoisted  in  the  usual 
manner.  The  method  of  untenting  a  tree  in  an  Eastern 
orchard  is  shown  in  Fig.  25.  On  very  large  trees  two 
lifters  are  usually  necessary,  and  in  this  manner  the 
weight  of  the  tent  can  be  kept  almost  entirely  from 
the  branches. 

California  outfit. — In  addition  to  the  descriptions 
of  the  apparatus  already  given  from  California,  Figs. 
26-29  will  be  °f  interest.  These  photographs  were 
furnished  by  R.  B.  Cundiff,  chairman  of  Riverside 
County  Board  of  Horticultural  Commissioners,  and 
were  taken  for  the  United  States  Department  of  Agri- 
culture for  the  Year-Book  of  1900.  It  will  be  seen 
by  the  figures  that  these  tents  are  of  enormous  size 
and  are  handled  by  two  lifters,  one  on  each  side  of  the 
tree,  Figs.  26  and  30.  The  tent  is  pulled  into  position 
very  much  in  the  same  manner  as  already  described. 
After  the  tree  is  covered,  as  shown  in  Figs.  27  and  31, 
the  canvas  is  folded  around  the  base  and  the  gas  is 
generated.  A  novel  feature  of  the  outfit  used  in  the 


CONSTRUCTION   AND   MANAGEMENT  OF  TENTS      57 

Riverside  district  is,  that  the  tents  are  removed  by 
means  of  a  horse,  as  shown  in  Fig.  28.  In  transport- 
ing these  tents  and  the  apparatus,  a  low-wheeled 


FIG.    3O — TENTING   AN    ORANGE    TREE    IN    RIVERSIDE    DISTRICT, 
CALIFORNIA 


wagon  is  used  on  which  the  entire  outfit  is  packed,  as 
shown  in  Fig.  29. 

When  using  a  large  tent  for  a  very  small  tree,  the 
tent  is  pulled  up  so  as  to  have  sufficient  slack  canvas 
to  cover  the  tree.  This  is  usually  pulled  over  by 
hand.  When  being  removed,  the  cloth  is  pulled  back 


FUMIGATION   METHODS 


FIG.    31 — TENT   IN    POSITION,    ABOUT    READY    FOR   CHEMICALS 

in  the  same  manner  and  dragged  along  the  ground  to 
the  next  tree.  Where  there  is  fear  of  breaking  the 
branches  in  removing  a  large  tent,  the  weight  is 
usually  taken  off  by  means  of  the  lifter.  The  tent,  by 
this  method,  slides  over  itself  and  protects  the  tree. 
It  is  transferred  from  tree  to  tree  in  accordance  with 
the  methods  already  described. 


CHAPTER  VIII 
EMORY    FUMIGATOR    WITH    MODIFICATIONS 

FTKR  much  experience  with  sheet  tents  in  East- 
ern orchards,  and  while  confident  the  gas 
could  be  used  to  good  advantage,  it  was  evi- 
dent to  the  writer  the  method  would  have  to 
be  simplified  before  it  could  be  used  by  the  average 
fruit  grower.  The  main  difficulty  was  in  the  calcula- 
tion of  the  cubic  contents  of  a  tented  tree  and  the 
measurement  of  the  chemicals  afterward.  The  folds 
in  a  tent  over  a  tree  are  so  extremely  variable  it  is 
almost  impossible  to  calculate  the  cubic  contents,  even 
approximately.  As  the  success  attained  by  this 
method  depends  entirely  upon  the  exactness  with 
which  the  operation  is  performed,  it  was  therefore 
necessary  to  find  a  system  less  variable  for  deciduous 
trees. 

First  of  all,  a  method  by  which  the  cubic  contents 
could  be  kept  nearly  constant,  and  one  that  could 
be  applied  without  the  wear  and  tear  upon  the 
tree  by  the  tent,  resulting  in  the  destruction  of  so 
many  fruit  and  leaf  buds,  was  desirable.  After  much 
thought  and  consideration,  it  seemed  that  both  ob- 
jections to  the  sheet  tent  system  could  be  overcome  by 
the  construction  of  a  box  with  a  square  base,  varying 
in  hight  to  suit  conditions  and  having  a  canvas  hood. 
It  was  also  necessary  to  cheapen  the  cost  of  the  equip- 
ment, if  possible. 

lyight  wooden  frames  were  constructed  and  covered 

59 


6o 


FUMIGATION   METHODS 


with  heavy  rawhide  building  paper.  The  largest  box 
was  six  feet  square  at  the  base  and  eight  feet  high,  as 
shown  in  Fig.  34.  It  was  put  together  with  three- 
inch  butt  hinges,  and  could  thus  be  easily  opened  by 
drawing  the  butts  from  one  side.  The  hood  is  made 


FIG.    32 — MODEL    TYPE    OF    EMORY    FUMIGATOR    WITH    HOOD 
FULLY    EXTENDED 

of  eight-ounce  ducking,  and  is  six  feet  four  inches  at 
the  base,  four  feet  square  at  the  top,  and  seven  feet 
high.  It  is  kept  in  place  by  means  of  cleats  around 
the  top  of  the  frame,  as  seen  in  Figs.  33  and  34. 


62  FUMIGATION   METHODS 

The  hood  is  first  placed  over  the  top  of  the  tree, 
•after  which  the  frame  is.  drawn  around  and  closed. 
After  the  bottom  of  the  hood  has  been  securely  fast- 
ened to  the  top  of  the  box  and  a  little  dirt  has  been 
thrown  around  the  bottom,  the  frame  is  tipped  back 
slightly  and  the  chemicals  are  introduced.  At  the  ex- 


FIG.  34 — EMORY  FUMIGATOR,  PAPER  TYPE,  COMPARED  WITH 
SHEET  TENT 

piration  of  the  proper  time  the  hood  is  removed, 
the  box  opened  and  slipped  around  the  next  tree. 
Boxes  under  six  feet  in  hight  were  constructed  with- 
out hoods  and  the  sides  screwed  together.  These  can 
be  handled  easily  and  can  be  used  on  small  trees, 
where  it  is  not  practicable  to  use  a  tent. 

It  was  slow  work  and  troublesome  to  place  the 
hood,  arrange  the  box,  and  get  it  ready  for  operation 
each  time.  The  system,  however,  was  as  near  perfect: 


64  FUMIGATION   METHODS 

as  we  could  expect  it,  and  we  began  work  to  overcome 
the  two  serious  objections.  First,  a  box  with  a  per- 
manent hood,  and,  seconcfty,  one  that  could  be  handled 
without  being  opened  on  the  sides  was  needed.  At  the 
same  time,  while  we  found  the  rawhide  paper  perfectly 
satisfactory  on  the  large  box,  it  was  quite  trouble- 
some to  put  on  the  frame  smoothly.  The  edges  were 
first  glued  and  then  nailed.  It  was  also  easily  punc- 
tured by  a  broken  limb  unless  great  care  was  taken. 
This  last  point  was  not  a  serious  objection,  and  little 
or  no  trouble  was  experienced  on  that  account.  A 
material,  however,  with  more  elasticity  was  desir- 
able. 

Taking  all  these  points  into  consideration,  a  box 
of  the  same  dimensions,  covered  with  eight-ounce 
ducking,  was  constructed.  The  sides  were  screwed  to- 
gether, and  the  hood  fastened  on  permanently  with 
narrow  strips  screwed  to  the  top  of  the  frame,  as 
shown  in  Fig.  32. 

Having  completed  this  box,  the  most  serious  obsta- 
cle arose.  How  could  a  box  of  such  dimensions,  with 
permanent  hood  and  sides,  be  handled  ?  There  was 
only  one  way  to  do  it,  and  that  was  to  pick  the  box 
up  and  lower  it  over  the  top  of  the  tree.  The  prob- 
lem was  solved  by  the  ingenuity  of  Robert  S.  Kmory. 
It  was  accomplished  by  means  of  a  thirty-five  foot 
mast  made  of  spar  pine  and  a  twelve-foot  gaff  of  the 
same  material.  It  was  fitted  with  ropes  and  pulleys, 
and  rigged  to  the  running-gear  of  an  ordinary  farm 
cart,  as  shown  in  Fig.  35.  By  means  of  this  it  could 
be  raised  and  lowered  over  any  tree  under  seventeen 
feet  in  hight.  The  system  worked  perfectly,  and  was 


66  FUMIGATION   METHODS 

applied  in  a  block  of  infested  pear  trees  the  first  and 
second  week  in  April,  1899. 

It  requires  three  or*four  men  to  operate  an  outfit 
of  this  kind  ;  the  help,  of  course,  depending  on  the 
number  of  fumigators  in  use.  It  requires  one  man  to 
look  after  the  chemicals  and  time,  and  two  or  three  to 
handle  the  fumigators  and  rigging.  With  an  equip- 
ment of  ten  fumigators  this  force,  under  favorable 
conditions,  can  in  one  day  fumigate  from  one  hundred 
and  seventy-five  to  two  hundred  trees,  varying  from 
twelve  to  seventeen  feet  in  hight.  The  cost  of  the 
chemicals  is  about  four  cents  for  the  eight-foot  box 
without  the  hood  extended,  five  to  six  cents  when  the 
hood  is  half  extended,  and  six  to  seven  cents  fully  ex- 
tended. 

The  cost  of  the  large  fumigator  complete,  as  seen 
in  Fig.  32,  is  about  $12,  or  about  two-thirds  that 
of  a  twenty-five  foot  sheet  tent  sufficient 'for  covering 
a  tree  of  the  same  size.  The  rigging  for  handling  the 
fumigators  costs  about  $12.  Taking  it  all  in  all, 
this  system  is  simple  and  can  be  used  by  the  average 
orchardist. 

In  giving  this  method  for  handling  hydrocyanic 
acid  gas  to  the  public,  it  should  be  said  that  the  author 
has  had  the  practical  experience  of  Robert  S.  Emory, 
of  Maryland,  without  which  it  would  not  have  been 
possible  to  have  completed  the  experiments  and  per- 
fected the  apparatus.  The  mechanical  details  were 
under  his  entire  personal  supervision.  As  a  slight  rec- 
ognition of  his  services  and  practical  experience,  this 
apparatus  has  been  named  the  ' '  Emory  Fumigator. ' ' 
The  Miller  type. — The  Emory  fumigator  has  been 


68 


FUMIGATION   METHODS 


modified  somewhat  by  H.  W.  Miller,  of  West  Virginia, 
types  of  which  are  sh(*vn  in  the  accompanying  illus- 
trations. It  is  constructed  for  use  in  orchards,  where 
the  trees  are  eight  to  ten  feet  high.  These  fumigators 


FIG.  38 — PLACING  FUMIGATOR  OVER  TREE. 
APPARATUS  FOR  CHEMICALS 


TRAY  AND 


are  five  feet  square  and  seven  feet  high,  with  flat  top. 
A  light  wrooden  frame  is  first  made,  around  which 
three  breadths  of  eight-ounce  ducking  (carefully  sewed 
together)  is  wrapped  and  tacked  along  one  edge  with 
tin  heads,  such  as  are  used  for  holding  building  paper 
in  place.  The  top  piece  of  cloth  is  also  tacked  around 


EMORY   FUMIGATOR   WITH   MODIFICATIONS 


69 


the  upper  edge  in  a  similar  manner.  The  cloth  is 
then  thoroughly  painted  with  boiled  linseed  oil  and 
allowed  to  dry.  Two  coats  are  given  if  necessary,  one 
being  applied  to  the  inside. 

To  facilitate  the  handling  of  these  fumigators  two 


FIG.    39 — FUMIGATOR    NEARLY    IN    POSITION 

strips  of  wood  are  nailed  on  opposite  sides,  as  shown  in 
Fig.  38  and  others.  At  the  top,  near  the  center,  a 
piece  of  half-inch  rope  two  to  three  feet  in  length  is 
tacked,  with  which  the  operator  can  easily  tip  the  tent 


7O  FUMIGATION   METHODS 

forward,  allowing  the  gas  to  escape  before  the  appara- 
tus is  transferred  from  »ne  tree  to  another. 

With  an  equipment  of  fifteen  fumigators  of  this 
type  three  hundred  to  four  hundred  trees  can  be  cov- 
ered in  a  day  at  a  cost,  including  labor  and  chemicals, 


FIG.    40 — PLACING   THE   CHEMICALS    UNDER   FUM1GATOR 

of  about  six  cents  per  tree.  For  an  outfit  of  this  char- 
acter in  mountain  orchards,  where  the  ground  is  rough, 
ten  men  are  necessary  to  manipulate  it  to  best  advan- 
tage. Three  men  handle  the  boxes,  as  shown  in  Fig. 
39.  It  also  requires  three  individuals  to  shovel  the 
earth  around  the  base  of  the  f umigator,  as  seen  in  Fig. 


EMORY   FUMIGATOR   WITH   MODIFICATIONS         71 


40.  Two  men  attend  to  the  chemicals,  weighing  the 
cyanide  and  measuring  the  acid  and  water,  as  shown 
in  Fig.  40.  In  this  particular  case  one  man  was  em- 
ployed to  level  the  ground  around  the  trees,  so  as  to 
facilitate  the  handling  of  the  fumigators.  A  general 


FIG.    41 — AIRING    THE    FUMIGATOR    JUST    BEFORE    REMOVAL 

foreman  and  timekeeper  was  necessary,  so  that  the 
boxes  could  be  transferred  at  the  proper  time  and 
without  delay. 

The  cost  of  the  fumigator  of  this  type  need  not  ex- 
ceed $5,  including  oil,  provided  the  work  is  done  at 
home.  The  outfit  illustrated  in  Figs.  36  and  37  is  a 
home-made  construction.  After  using  fumigators  of 
this  type  the  canvas  can  be  easily  removed  and  used 


72  FUMIGATION   METHODS 

for  other  purposes  in  orchards  and  farm  work.  In 
some  cases  the  sheets  are  used  to  cover  fruit  in  wagons 
as  it  is  hauled  to  the  station.  The  frames  are  put  to- 
gether with  nails  or  screws,  and  are  easily  taken  to 
pieces  and  stored  away  for  future  use.  This  type  of 
f umigator  is  valuable  for  small  trees  and  shrubs  in  or- 
chards and  on  private  grounds.  The  method  of  oper- 
ating this  type  of  fumigator  is  shown  in  Figs.  36  to 
42,  taken  by  the  author  expressly  for  this  work. 

A  box  fumigator. — A  new  style,  much  after  the 
old  type  of  the  Emory  fumigator,  has  been  designed  by 
Prof.  V.  H.  Lowe,  of  the  New  York  Experiment  Sta- 
tion. It  is  intended  for  use  with  the  smaller  orchard 
trees,  such  as  peach,  pear,  plum,  and  quince.  A  good 
idea  of  the  general  construction  of  this  apparatus  can 
'be  gotten  from  a  study  of  Fig.  43.  The  dimensions 
are  10  x  6  x  6  feet.  The  frame  consists  of  well-sea- 
soned pine  strips  three  inches  wide  and  seven-eighths 
inches  thick,  braced  on  three  sides  by  double  cross- 
pieces  of  the  same  thickness  and  one  and  one-fourth 
inches  wide.  The  base  is  made  of  four-inch  strips 
and  has  but  three  sides,  the  fourth  being  omitted  to 
avoid  the  necessity  of  lifting  the  generator  from  the 
top  of  the  tree  before  putting  it  in  place.  The  frame 
is  covered  with  eight-ounce  ducking,  such  as  described 
for  the  Emory  tents  and  other  fumigators.  The  cloth 
was  oiled  with  boiled  linseed  oil,  in  which  lampblack 
was  mixed  to  give  it  a  dark  color.  To  prevent  trees 
from  penetrating  the  top  of  the  fumigator  a  stout  wire 
netting  was  tacked  on  the  inside  of  the  upper  half  of 
the  frame. 

A  strip  of  canvas  one  and    one-half   feet  wide  was 


EMORY   FUMIGATOR    WITH   MODIFICATIONS 


73 


attached  to  each  side  of  the  base  of  the  frame.  The 
strips  lap  at  the  corners,  so  that  when  the  fumigator  is 
in  place  they  lie  on  the  ground  and  can  be  covered 
with  dirt  or  sand-bags,  thus  preventing  the  escape  of 


FIG.   42 — TRANSFERRING    THE    FUMIGATOR 

the  gas.  These  strips  can  be  hooked  up  and  kept  out 
of  the  way  when  the  fumigator  is  being  carried  from 
one  tree  to  the  other.  The  movable  side  of  the  fumi- 
gator can  be  easily  put  in  place  or  taken  off.  It  is 


EMORY   FUMIGATOR   WITH    MODIFICATIONS         75 

provided  with  four  handles,  as  shown  in  the  illustra- 
tion. There  is  a  two-inch  flange  covered  with  a  good 
quality  of  felt,  against  which  the  door  rests.  The  sur- 
face of  the  frame  which  rests  against  the  flange  is  cov- 
ered with  the  same  material.  There  are  two  flat 
pieces  projecting  on  each  side  from  the  base  of  the 
frame  upon  which  the  door  rests.  There  are  thirteen 
buttons  by  which  the  door  is  fastened  and  kept  in 
place,  as  illustrated. 

The  cost  of  a  fumigator  of  this  size  varies  from 
$13  to  $18,  according  to  the  material  used  in  its 
construction.  This  fumigator  has  been  severely  tested 
at  the  New  York  Experiment  Station  and  found 
very  satisfactory.  The  time  required  for  moving  it 
from  one  tree  to  another  varies  somewhat  with  con- 
ditions, but  as  a  rule  it  can  be  set  up  in  from  ten  to 
fifteen  minutes.  It  can  be  operated  and  easily  carried 
by  two  men.  A  fumigator  12x8x8  feet,  built  accord- 
ing to  this  style,  would  no  doubt  be  practical,  and 
would  require  about  three  men  to  handle  it.  The  re- 
moval of  one  side  prevents  the  necessity  of  lifting  it 
over  the  tree,  as  is  the  case  with  the  Emory  type. 


CHAPTER   IX 
ESTIMATING    GAS    FOR    ORCHARD    WORK 


A 


MOUNTS  OF  CHEMICALS. — The  foreman  or  super- 
intendent should  be  responsible  for  the  chem- 
icals used  for  making  the  gas.  As  a  rule, 
where  the  sheet  tents  are  used,  different 
amounts  are  necessary  for  individual  trees,  espe- 
cially where  they  vary  in  size.  The  superintendent 
judges  the  size  of  the  tree  as  soon  as  it  is  tented, 
and  estimates  and  weighs  the  chemicals  accord- 
ingly. It  is  difficult  to  estimate  the  cubic  contents 
of  a  tented  tree,  and  as  a  result  some  unsatisfac- 
tory work  is  done.  Indeed,  it  is  surprising  that  the 
results  are  as  uniform  as  they  are.  In  California  the 
trees  to  be  fumigated  are  usually  inspected  in  advance, 
so  that  the  superintendent  can,  in  a  general  way,  esti- 
mate the  amount  of  gas  necessary.  A  little  more  gas 
than  the  tree  will  stand  without  injury  is  usually  pro- 
duced. This  is  somewhat  misleading,  for  the  larger 
the  tree  the  greater  the  injury.  If  the  dose  is  properly 
proportional  to  the  cubic  content,  there  is  a  slower 
diffusion  of  the  gas,  in  which  case  care  must  be  taken 
when  large  trees  are  fumigated. 

The  usual  method  is  to  measure  the  tree  and  find 
the  amount  of  chemicals  necessary  -by  reference  to  a 
table  prepared  for  that  purpose.  If  the  tables  are  cor- 
rectly calculated  and  the  measurement  accurately  done 
this  is  perhaps  the  safest  method.  As  already  indi- 
76 


ESTIMATING   GAS   FOR   ORCHARD   WORK  77 

cated,  it  is  difficult  to  measure  and  determine  accurately 
the  cubic  content  of  a  tented  tree.  To  simplify  the 
measurement  and  estimation  of  the  tent  the  following 
table  has  been  prepared  by  Prof.  Woodworth,  of  Cali- 
fornia. The  center  column  gives  the  various  doses 
corresponding  to  the  size  of  the  trees  in  the  columns 
on  either  side.  Thus,  on  one  side  it  has  been  calcu- 
lated so  as  to  give  three  parts  of  hydrocyanic  acid  gas 
in  1000  parts  of  air  ;  on  the  other  side,  two  parts  in 
1000  of  air.  For  winter  treatment  for  deciduous  trees 
the  first  or  0.3  per  cent,  gas  is  suggested.  This  is 
about  equivalent  to  the  general  recommendations  given 
for  the  Eastern  States.  One-half  of  this  amount  is  not 
far  from  the  commonest  practice  in  California  for 
citrus  trees.  The  0.2  per  cent,  formula  is  suggested 
for  citrus  trees.  It  agrees  with  the  amounts  used  by 
some  of  the  most  successful  fumigators  in  California. 
Other  individuals  get  fair  results  with  scarcely  more 
than  half  this  amount. 

The  measurements  to  be  taken  when  using  this 
table  are  (i)  around  the  tent,  and  (2)  from  the 
tent  from  ground  to  ground.  If  these  two  measure- 
ments are  about  equal,  as  will  be  found  on  many 
orange  trees,  the  number  nearest  the  measure- 
ment is  found  in  the  circumference  column,  and 
the  corresponding  dose  will  be  seen  in  the  center 
column.  If  these  two  measurements  are  not  nearly 
the  same,  the  outside  columns  become  useful,  for 
they  show  for  each  size  how  much  difference  must 
occur  to  make  necessary  a  half  ounce  increased  or  de- 
creased in  dose  ;  that  is.  for  each  differential  there  must 
be  added  or  deducted  one-half  ounce  of  cyanide.  For 


FUMIGATION   METHODS 


instance,  if  the  difference  between  the  distance  over 
and  around  the  tree  is  fivejeet,  and  the  differential  for 
the  circumference  is  three  feet  eleven  inches,  then  the 
dose  must  be  increased  or  diminished  by  a  little  more 
than  a  half  ounce  ;  but  if  the  differential  is  one  foot, 
then  for  each  foot  there  must  be  added  or  subtracted 
one-half  ounce,  or  two  and  a  half  ounces  for  the  five 
feet. 

CYANIDE   NECESSARY  FOR  TREES  OF  VARIOUS  SIZE& 
IN   CALIFORNIA 


0.3   PER   CENT.    GAS 

CYANIDE 

0.2   PER  CENT.    GAS 

^  Ounce 
Differential 

Circu  mferen  ce 
of  Tree 

Circumference 
of  Tree 

1^  Ounce 
Differential 

Ft.   In. 

Ft.    In. 

Ounces 

Ft.   In. 

Ft.   In. 

3      5 

19      1 

2 

22      1 

3    11 

3 

20      6 

2/^3 

23      7 

3      4 

2      7 

21    11 

3 

25 

2    11 

2      4 

23 

26      4 

2      8 

2      2 

24      1 

4 

27      7 

2      6 

1     11 

25      1 

4Vi» 

28      9 

2      4 

10 

26 

5 

29    10 

2      2 

9 

26    10 

51^ 

30      9 

2 

8 

27      8 

6 

31      8 

1     10 

7 

28      5 

32      7 

1      9 

6 

29      1 

7 

33      4 

1      8 

5 

29      9 

7^ 

34 

1      7 

4 

30      4 

8 

34      8 

1      6 

3 

31      6 

9 

36      1 

1      5 

2 

32      7 

10 

37      5 

1      4 

1 

11 

38      7 

1      3 

34      8 

12 

39    10 

1      2 

11 

35      7 

13 

40    11 

1       1 

10 

36      6 

14 

41     11 

1      1 

10 

37      5 

15 

42    10 

1 

9 

38      3 

16 

43      9 

11 

9 

39 

17 

44      8 

11 

8 

39      9 

18 

45      7 

10 

8 

40      5 

19 

46      5 

10 

7 

41      2 

20 

47      3 

10 

7 

42      8 

22 

48      9 

9 

7 

43    11 

24 

50      2 

9 

6 

45 

26 

51      6 

8 

6 

46      1 

28 

52      8 

8 

6 

47      2 

30 

54 

7 

5 

48      2 

32 

55      3 

7 

ESTIMATING   GAS   FOR   ORCHARD   WORK  79 

As  an  example,  Professor  Woodworth  cites  a  tree  35 
feet  around  and  36  feet  over  the  top,  using  the  0.2  per 
cent,  table.  Running  down  the  circumference  column 
we  find  that  34  feet  8  inches  (the  nearest  to  35  inches) 
requires  8  ounces,  and  that  the  differential  is  i  foot 
6  inches;  that  is,  35  feet  requires  a  little  over  8  ounces, 
and  the  difference  between  the  two  measurements 
around  and  over  the  tree,  i  foot,  is  nearly  enough  to 
require  another  half  ounce,  so  that  S}4  ounces  would 
be  about  right.  Suppose,  again,  the  distance  around 
a  tree  to  be  40  feet,  and  that  over  the  top  only  35  feet; 
using  the  same  table,  we  find  opposite  39  feet  10  inches 
(the  nearest  to  40  feet)  the  dose  12  ounces.  But  the 
distance  over  the  top  is  5  feet  less,  and  a  less  amount 
of  cyanide  will  be  necessary.  We  therefore  use  the 
differential  (i  foot  2  inches)  and  deduct  one-half 
ounce  for  each  i  foot  2  inches  difference,  or  about  2 
ounces  altogether.  This  leaves  10  ounces  as  the  correct 
dose  for  this  tree.  These  measurements  are  not  sup- 
posed to  be  taken  with  every  tree,  but  in  cases  of 
doubt,  and  occasionally  to  correct  one's  judgment; 
and  in  the  case  of  those  beginning  to  fumigate,  whose 
judgment  is  not  yet  developed. 

The  three  tables  following  are  taken  from  an 
excellent  article  on  fumigation  in  the  Rural  Cali- 
fornian.  Effectiveness  demands  accurate  judgment  as 
to  the  quantities  of  the  chemicals  to  be  used.  This 
must  necessarily  vary  according  to  the  cubic  space  to 
be  filled  with  gas,  or,  in  other  words,  according  to  the 
size  of  the  tree.  The  tables  here  given,  based  on  the 
hight  and  width  of  tree,  will  be  found  quite  practicable, 
but  in  order  to  eliminate  as  far  as  possible  errors  of 


8o 


FUMIGATION    METHODS 


judgment  regarding  the  dimensions  of  the  trees  to  be 
fumigated,  a  stick  marked  off  in  feet  will  be  of  assist- 
ance. 

QUANTITY   OF   CHEMICALS  TO   DESTROY   BI^ACK   SCAI,E   ON 
CITRUS   TREES 


HIGHT 

Diameter 

Water 

Sulphuric  Acid 

Cyanide 

Feet 

Feet 

Ounces 

Ounces 

Ounces 

6 

4 

2 

1W 

V& 

8 

6 

5 

1/4 

1/4 

10 

8 

7 

2 

2 

12 

10 

12 

3 

4J^> 

12 

14 

18 

4/^J 

4^i 

14 

14 

20 

5  " 

5 

16 

16 

24 

5Jx> 

5Vij 

18 

16 

24 

6 

6 

20 

16 

26 

6/^ 

6}^ 

22 

18 

30 

714 

7/4 

24 

20 

88 

8 

8 

26 

20 

88 

8^6 

8J4 

30 

20 

35 

8^ 

m 

The  proportions  of  chemicals  used  for  citrus  trees 
affected  with  red,  brown,  or  purple  scale  are  given  in 
the  following  table.  The  same  quantity  may  be  used 
for  deciduous  trees  infested  with  San  Jose  or  black 
scale. 

CHEMICALS  FOR  RED,   BROWN,   AND   PURPLE    SCAI.E 


HIGHT 

Diameter 

Water 

Sulphuric  Acid 

Cyanide 

Feet 

Feet 

Ounces 

Ounces 

Ounces 

6 

4 

3 

lur 

3^ 

8 

6 

7J4 

1% 

1% 

10 

8 

»y% 

3 

3 

12 

10 

18 

4J*ij 

4/^j 

12 

14 

27 

0% 

6M 

14 

14 

30 

7^3 

7J^ 

16 

16 

36 

8j4 

8^4 

18 

16 

36 

9 

9 

20 
22 

16 

18 

39 
45 

10% 

m 

10% 

24 

20 

48 

12  8 

12 

26 

20 

49^ 

12% 

12% 

30 

20 

51V| 

w» 

12^ 

ESTIMATING   GAS   FOR    ORCHARD   WORK 


8l 


On  low,  damp  grounds  where  fogs  are  frequent, 
and  especially  for  apple  and  pear  trees,  infested  with 
either  the  San  Jose  scale  or  codlin  moth,  or  old  seedling 
orange  trees  infested  with  red,  brown,  or  purple  scale, 
the  following  table  should  be  used: 

CHEMICALS  FOR  ORCHARDS  ON  DAMP  GROUNDS  OR  WHERE 
FREQUENT  FOGS  OCCUR 


HIGHT 

Diameter 

Water 

Sulphuric  Add 

Cyanide 

Feet 

Feet 

Ounces 

Ounces 

Ounces 

6 

4 

4 

1 

1 

8 

6 

10 

10 

8 

14 

4 

4  4 

12 

10 

24 

6 

6 

12 

14 

36 

9 

9 

14 

14 

40 

10 

10 

16 

16 

48 

11 

11 

18 

16 

48 

12 

12 

20 

16 

52 

13 

13 

22 

18 

60 

24 

20 

64 

16 

16 

26 

20 

66 

16# 

30 

20 

70 

17 

17 

In  the  tables  given  above  the  diameter  is  taken 
through  the  foliage.  The  water  and  acid  are  estimated 
in  fluid  ounces. 

In  Eastern  orchards  the  amount  of  cyanide  is  some- 
what greater  than  that  used  in  California.  Experience 
has  shown  that  0.20  gramme  of  cyanide  per  cubic  foot 
of  space  enclosed  gives  most  satisfactory  results  upon 
scale-infested  deciduous  trees  in  the  Hast. 

In  the  preparation  of  the  following  table  calcula- 
tions are  based  on  the  hight  and  diameter  of  the  tented 
tree.  First,  the  cubic  contents  of  a  cylinder  was  cal- 
culated, the  hight  and  diameter  of  which  was  the 
hight  and  diameter  of  the  tree,  then  the  contents  of  a 
sphere  wrhose  diameter  was  the  hight  of  the  tree  was 


82 


FUMIGATION   METHODS 


estimated.  By  taking  half  the  difference  and  adding 
it  to  the  contents  of  the  cylinder  the  estimation  was 
found  approximately  correct. 

CHEMICALS  ESTIMATED   FOR   EASTERN   ORCHARDS 


HIGHT  OF 
TREE 

Diameter 

Cyanide 

Acid 

Water 

Feet 

Feet 

Grammes 

Ounces 

Ounces 

4 

3 

6.17 

0.32 

0.48 

5 

4 

12.82 

0.67 

1.00 

6 

4 

18.85 

1.00 

1.50 

7 

4 

26.75 

1.41 

2.11 

Ounces 

7 

5 

.1.11 

1.66 

2.49 

8 

4 

1.30 

1.95 

2.92 

9 

5 

1.50 

2.25 

3.39 

9 

5 

1.96 

2.94 

4.41 

g 

6 

2.24 

3.36 

5.00 

10 

7 

3.20 

4.80 

7.20 

10 

8 

3.62 

5.43 

8.14 

11 

7 

3.95 

5.92 

8.88 

11 

8 

4.40 

6.60 

9.90 

12 

9 

5.88 

8.82 

13.23 

12 

10 

6.51 

9.76 

14.64 

13 

9 

6.93 

10.39 

15.58 

13 

10 

7.65 

11.47 

17.20 

14 

11 

9.76 

14.64 

21.96 

14 

12 

10.65 

15.97 

2345 

15 

11 

13.28 

19.42 

29.88 

15 

12 

14.24 

21.36 

32.04 

16 

14 

16.34 

24.51 

36.76 

16 

15 

17.53 

26.27 

39.43 

17 

14 

18.39 

27.57 

41.35 

17 

15 

19.36 

29.40 

44.23 

18 

15 

22.06 

33.09 

49.63 

19 

16 

26.10 

39.15 

58.72 

20 

16 

29.00 

43.50 

65.25 

A  careful  study  of  the  tables  made  by  various  indi- 
viduals for  orchard  work  is  interesting.  The  present 
practice  in  California  does  not  vary  much  in  amount 
of  cyanide  used  per  cubic  foot  from  that  originally 
estimated  by  Coquillett  and  Morse.  The  results  as 
summed  up  by  Woodworth  are  given  in  the  following 
table. 


ESTIMATING  GAS   FOR   ORCHARD   WORK 


COMPARATIVE  VAIyUE  OF  CYANIDE   PER  CUBIC   FOOT  FOR 
ORCHARD  WORK 


DATE 

Name 

Capacity  per  Ounce  of  Cyanide 

1887 

F.  W.  Morse 
D.  W.  Coquillett 
D.  W.  Coquillett 
Alexander  Craw 
T.  B.  Johnson 
C.  W.  Woodworth 
W.  G.  Johnson 

145  cu 
95 
165 
352 
242 
300 
80 

bicfe 

et 

1888  
1889  
1891 

1894  

1896      .       .  . 

1898  

CHAPTER  X 

DAYLIGHT    FUMIGATION    AND    COST    OF 
APPLICATION 


N  California  experience  has  shown  that  the 
citrus  orchards  can  not  be  successfully  fumi- 
gated during  the  day.  On  the  other  hand, 
in  the  East,  in  deciduous  orchards,  daylight 
fumigation  has  been  found  most  practicable.  As  a 
rule,  Eastern  orchards  are  fumigated  during  the  fall, 
after  growth  is  stopped  and  after  the  function  of  the 
foliage  has  been  performed.  In  such  instances  it  mat- 
ters little  whether  or  not  the  foliage  is  injured  by  the 
gas.  In  Fig.  44  will  be  seen  a  Japanese  plum  tree,  one 
of  a  block  of  5,000,  fumigated  in  October  with  the  0.20 
gramme  formula.  While  these  trees  were  fumigated 
in  daylight,  the  foliage  in  this  particular  instance  was 
practically  uninjured.  In  some  cases  where  the  fumi- 
gators  were  left  over  the  trees  longer  than  thirty  min- 
utes, the  foliage  was  somewhat  seered,  but  no  injury 
resulted  to  the  trees.  By  referring  to  Chapter  III.  it 
will  be  seen  that  the  physiological  effect  of  this  gas 
varies  with  certain  kinds  of  trees,  and  is  influenced  by 
weather  conditions  and  time  of  day. 

In  the  Eastern   orchards  the  gas  is   best   applied 
during  the  daytime  late  in  the  fall  or  early  spring,  as 
will  best  suit  conditions  and  circumstances.     In  Fig. 
84 


DAYLIGHT   FUMIGATION,    COST    OF   APPLICATION    85 

24  the  apparatus  was  used  in  the  plum  orchard  during 
the  month  of  March .  The  buds  had  j  ust  begun  to  swell , 
but  no  injury  was  noted,  while  the  scale  was  destroyed. 


FIG.    44 JAPANESE    PLUM    TREE    IN    FULL    FOLIAGE 

FUMIGATED    IN   OCTOBER 

In  the  fumigation  of  nursery  stock,  especially  in  the 
house,  it  makes  little  or  no  difference  at  what  time  of 
the  day  the  trees  are  fumigated. 

Expert  Opinion. — There  has  been  considerable  dis- 


86  FUMIGATION   METHODS 

• 

cussion  regarding  daylight  fumigation  in  California. 
The  following  interesting  letter  from  R.  P.  Cundiff ,  an 
expert  on  this  subject  and  Chairman  of  the  Riverside 
County  Board  of  Horticultural  Commissioners,  is  of 
timely  interest:  "What  I  say  upon  this  subject  is 
mainly  from  a  local  standpoint.  While  I  seriously 
doubt  the  practicability  of  daylight  fumigation  in  any 
locality  of  southern  California,  I  am  not  prepared  to 
maintain  that  in  some  localities,  during  certain 
climatic  conditions,  and  for  some  varieties  of  scale,  it 
might  not  be  done  with  reasonable  safety.  However, 
I  know  of  no  practical  fumigator  who  has  ever  advo- 
cated it.  I  am  under  the  impression  that  those  who 
are  giving  such  learned  opinions  on  this  subject  are 
possessed  of  more  of  a  theoretical  than  practical  knowl- 
edge of  fumigation  by  hydrocyanic  acid  gas. 

4 '  In  Riverside  County  we  have  found  it  necessary 
to  fumigate  but  little  for  black  scale,  for  it  has  never 
assumed  the  proportions  of  a  serious  pest,  as  in  some 
of  the  coast  counties.  Our  fumigation  has  been  almost 
entirely  for  red  scale.  It  is  a  well-known  fact  among 
fumigators  that  it  requires  almost  double  the  quantity 
of  cyanide  to  kill  red  scale  that  it  does  for  black  or 
brown  scale.  This  must  be  taken  into  account  when 
we  come  to  discuss  the  proposition  of  daylight  fumiga- 
tion. Another  consideration  is  the  difference  in  tem- 
perature. Riverside,  being  an  interior  county,  is  sub- 
jected to  several  degrees  more  heat  than  localities  near 
the  coast.  Another  point  that  should  be  considered  is 
the  season  of  the  year  when  the  work  is  performed. 
Fumigation  for  black  scale,  to  be  in  any  degree  effect- 
ive, must  be  done  during  the  fall  and  winter  months. 


DAYLIGHT   FUMIGATION,    COST  OF   APPLICATION   87 

Especially  is  this  true  of  I^os  Angeles,  Orange,  and 
San  Diego  counties,  where  ordinarily  an  orchard  is 
fumigated  but  once  a  year.  In  any  of  these  counties 
from  October  until  March  is  considered  the  best  time. 
During  this  period  the  scale  is  young  and  will  yield 
quite  readily  to  treatment  by  fumigation. 

' '  As  fumigation  for  red  scale  seems  to  be  equally 
effective  at  all  times  of  the  year,  in  order  to  incur  the 
least  damage  to  the  grower,  in  the  way  of  knocking  off 
fruit,  etc.,  also  to  avoid  rainy  weather  and  north 
winds,  we  have  made  a  practice  in  Riverside  County  of 
doing  the  greater  part  of  the  fumigation  between  the 
months  of  May  and  December.  This  period  embraces 
our  warmest  weather.  In  this  connection  I  wish  to 
refer  to  a  matter  that  has  evidently  escaped  the  atten- 
tion of  the  advocates  of  daylight  fumigation.  During 
our  summer  months  we  have  periods,  sometimes  ex- 
tending over  many  days,  when  the  mercury  will  range 
in  the  nineties.  With  a  temperature  of  from  90  to  95 
degrees  we  are  quite  sure  that  by  enclosing  a  tree 
under  an  air-tight  tent  for  the  time  required  for  fumi- 
gation, which  is  from  40  to  45  minutes,  the  tempera- 
ture under  the  tent  would  be  increased  from  25  to  30 
degrees.  Add  to  this  the  increased  heat  caused  by 
generating  the  chemicals,  which  would  be  perhaps 
10  degrees  more,  and  the  resulting  temperature  would 
very  likely  do  harm.  It  is  well  known  that  a  citrus 
tree  will  not  stand  a  temperature  of  135  degrees  for 
any  length  of  time  without  serious  results.  We  know 
from  actual  observation  that  the  action  of  sunlight  upon 
hydrocyanic  acid  gas  has  a  scalding  or  burning  effect 
upon  foliage.  Practically  all  of  the  damage  ever  done 


88  FUMIGATION   METHODS 

in  Riverside  County  from  fumigation  with  cyanide  has 
been  caused  by  an  occasional  mistake  of  the  foreman  of 
fumigation  in  either  beginning  his  work  too  early  in 
the  evening  or  continuing  it  too  late  in  the  morning. 
This  has,  however,  seldom  occurred,  as  few  fumiga- 
tors  who  understand  their  business  will  risk  their 
reputations  by  taking  such  chances.  I  recall  to  mind 
a  suit  brought  against  the  county  some  years  ago  for 
alleged  damages  by  one  of  our  growers.  This,  I  un- 
understand,  was  a  case  of  daylight  fumigation. 

' '  I  quite  agree  with  the  advocates  of  daylight 
fumigation  that  there  would  be  some  advantages 
gained  by  doing  the  work  in  the  daytime  instead  of 
night.  There  would  be  a  small  saving  in  chemicals, 
but  not  nearly  so  much  as  claimed  by  some.  It  would 
be  also  easier  to  locate  trees  and  move  the  apparatus 
from  place  to  place.  On  the  other  hand,  there  are 
some  advantages  in  doing  the  work  at  night.  The 
handling  of  a  fumigating  outfit,  especially  where  large 
tents  are  required,  is  very  laborious.  Men  could  do 
more  work  with  less  fatigue  on  account  of  the  cooler 
temperature.  This  would  be  especially  true  in  River- 
side County,  where  the  greater  part  of  the  fumigation 
is  done  during  the  warm  months.  I  am  under  the 
impression  that  it  would  be  difficult  to  get  men  to  work 
during  the  very  warm  weather  in  the  daytime,  as  the 
reflection  of  the  sunlight  on  the  tents  would  increase 
the  heat  to  such  an  extent  that  they  would  prefer 
other  work  at  less  wages.  As  was  intimated  at  the 
beginning,  it  is  probable  that  in  some  of  the  coast 
counties,  in  fumigating  for  black  scale,  where  the 
amount  of  cyanide  is  much  less  than  for  red  scale, 


DAYLIGHT   FUMIGATION,    COST   OF   APPLICATION   89 

fumigating  could  be  done  on  cool,  cloudy  days  with 
comparative  safety.  But  in  Riverside  County,  where 
the  fumigation  is  almost  entirely  for  red  scale,  where  a 
much  greater  amount  of  cyanide  is  required,  and 
where  it  is  necessary  to  do  the  work  during  the  warm 
weather,  it  would  certainly  be  a  very  unsafe  thing  to 


FIG.    45 — CHARGING   A    CALIFORNIA    HOO.P   TENT 

do.  And  the  orchardist  who  attempts  it  will  probably 
be  reminded  of  this  fact  by  having  his  trees  damaged. ' ' 
The  cost  of  or  chard  fumigation  depends  upon  the  loca- 
tion of  the  orchard,  the  kind  and  size  of  the  tree,  and, 
to  a  certain  extent,  upon  the  prevailing  weather  condi- 
tions under  which  the  work  is  done.  The  actual  cost  of 
fumigation  is  not  necessarily  very  great  after  the  out- 
fit is  once  secured.  With  a  small  number  of  Emory 
fumigators,  or  sheet  tents,  most  fruit  growers  can  apply 


90  FUMIGATION   METHODS 

the  gas  method  withouj:  difficulty  if  the  rules  given 
herewith  are  carefully  followed. 

Ivarge  outfits  are  so  expensive  it  is  desirable  in 
many  cases  for  the  state,  county,  or  local  society  to 
own  the  tents  and  other  equipment.  In  California 
especially,  where  it  is  necessary  to  operate  at  night, 
these  outfits  are  practically  controlled  by  county  and 
local  organizations.  The  number  of  persons  necessary 
to  operate  a  system  of  fumigators  depends  somewhat 
on  the  size  of  the  trees  and  the  number  and  kind  of 
tents.  One  or  two  men  introduce  the  chemicals, 
others  look  after  the  vessels,  measure  the  acid  and 
water,  while  others  manipulate  the  tents.  As  soon  as 
the  tent  is  in  place,  the  fumigator  enters  it,  introduces 
the  chemicals,  withdraws  quickly,  closes  the  tent,  and 
proceeds  to  the  next  tree.  In  many  cases  the  assistant 
raises  the  edge  of  the  tent,  while  the  fumigator  enters 
and  drops  it  as  soon  as  he  comes  out.  The  wagon 
containing  the  chemicals  is  then  drawn  to  the  next 
tree.  The  generator  beneath  the  tree  just  fumigated 
is  removed,  and  the  contents  poured  on  the  ground  near 
the  trunk  of  the  tree.  The  acid  and  water  are  meas- 
ured, carried  to  the  next  tent,  and  introduced,  as  shown 
in  Fig.  45.  Various  appliances  are  used  for  carrying 
and  handling  the  chemicals  in  an  orchard  in  the  east. 
A  wheelbarrow  or  small  hand-cart  has  been  found  very 
useful,  as  shown  in  Fig.  22.  In  other  cases  a  small, 
table-like  tray  is  used  to  carry  the  apparatus,  as  seen 
in  Fig.  38. 

The  location  of  an  orchard  and  its  freedom  from 
dampness  and  fog  must  be  considered.  The  ground, 
trees,  and  the  leaves  should  be  dry  when  fumigated. 


DAYLIGHT    FUMIGATION,    COST   OF   APPLICATION    91 


If  perceptibly  damp  the  gas  is  more  liable  to  burn  the 
foliage.  After  irrigation,  where  it  is  practical,  the 
ground  should  be  allowed  to  become  quite  dry  before 
the  fumigation  operations  begin.  When  trees  are  wet 
with  dew  or  a  slight  rain,  care  should  be  taken  to  see 
that  they  are  fairly  dry  before  being  tented.  In  some 


FIG.    46 — WAGON    FOR    CARRYING    CHEMICALS    IN    ORCHARD 

instances  fumigation  in  Eastern  orchards  can  not  be 
commenced  before  nine  or  ten  o'clock  in  the  morning 
or  until  the  trees  are  dry. 

Care  of  tents. — When  a  large  fumigating  outfit  is  in 
operation  each  tent  should  be  thoroughly  inspected 
daily.  In  most  cases  this  can  be  done  to  best  advantage 
wrhen  the  tent  is  over  the  tree.  The  inspector  should  go 
under  the  tent  and  carefully  examine  it.  If  there  are 


92  FUMIGATION   METHODS 

any  holes  in  it  they  *can  be  easily  detected.  The 
places  should  be  marked  and  patched  at  once.  Some- 
times a  patch  is  glued  on,  but  it  is  preferable,  in  most 
cases,  to  sew  them  on  in  the  usual  manner.  For  tem- 
porary purposes  a  small  stone,  nut,  or  even  dirt,  tied  in 
the  rupture  will  answer  until  it  can  be  patched. 


CHAPTER  XI 
EQUIPMENT  FOR  FUMIGATING  NURSERY  STOCK 

T""!HK  enclosure  necessary  for  fumigating  purposes 
.  in  nurseries  varies  considerably.  In  some 
cases  boxes  will  accommodate  the  grower, 
but  the  building  is  usually  constructed  in 
accordance  with  the  number  of  trees  grown  or  handled. 
Some  nurserymen  have  found  it  necessary  to  construct 
a  house  large  enough  to  hold  12,000  to  15,000  first- 
class  trees  at  one  time.  Some  firms  handling  a  million 
or  more  trees  annually  have  rooms  large  enough  to 
admit  a  wagon-load  of  trees  at  one  time,  examples  of 
which  are  given  in  Figs.  52  and  64. 

A  good  tent,  such  as  is  seen  in  Fig.  12,  can  be  used 
in  cases  of  emergency,  but  it  is  not  advisable  to  de- 
pend upon  a  tent  altogether.  Many  nurserymen  have 
found  a  small  box  tent,  similar  to  the  one  shown  in 
Fig.  32,  very  useful.  Still  others  have  used  a  sheet 
tent  over  a  wagon-load  of  trees  to  good  advantage. 
There  are  some  objections  to  a  tent  or  box  covered 
with  canvas  ;  in  the  first  place,  by  constant  use  it  is 
liable  to  be  torn,  and,  secondly  (and  most  important), 
the  cubic  capacity  of  space  enclosed  under  a  sheet  tent 
will  vary  with  the  amount  of  stock  fumigated.  Herein 
lies  the  greatest  source  of  error,  inasmuch  as  the 
chemicals  must  be  weighed  every  time  for  each  indi- 
vidual lot  of  trees  treated.  Where  the  box  or  Emory 

93 


94  FUMIGATION   METHODS 

fumi gator  is  employed,  however,  this  difficulty  is  over- 
come, as  the  cubic  content  is  constant  and  the  amount 
of  chemicals  used  does  not  vary.  The  danger  of  error 
is  eliminated  when  a  box  or  house  is  used.  It  matters 


FIG.  47 — BOX  USED  BY  SOME  NURSERYMEN  IN  THE  SOUTH 
(AFTER  SHERMAN) 

not  whether  one  or  several  thousand  trees  are  placed 
in  the  enclosure,  the  amount  of  gas  generated  must  re- 
main constant. 

Small  boxes. — Many  nurserymen  find  small  boxes 
very  useful.  Fig.  47  is  a  box  used  in  North  Carolina. 
The  details  for  construction  are  given  by  Prof.  Frank- 


EQUIPMENT   FOR   FUMIGATING   NURSERY  STOCK    95 

lin  Sherman,  State  Entomologist  of  North  Carolina. 
Build  box  of  plain  matched  three-quarter  inch  ceiling, 
making  walls,  top,  and  bottom  double,  with  two  thick- 
nesses of  rosin-sized  or  tarred  paper  between.  Rein- 
force the  corners  with  1^x3  inch  stuff,  and  stiffen 
the  corners  with  2x3  inch  battens. 

Make  the  uprights  of  2  x  6  inch  stuff,  and  the  two 
keying  beams  of  2  x  8  inch  stuff,  ceiling  to  be  in  con- 


FIG.  48 — TYPE  OF  BOX  USED  BY  SOME  CANADIAN  NURSERYMEN 
(AFTER  LOCHHEAD) 

tinuous  pieces,  and  all  joints  to  be  wiped  with  white 
lead  and  driven  up  close.  Give  the  box  two  good 
coats  of  lead  and  oil  paint,  both  inside  and  out,  and 
repeat  each  year.  The  size  of  the  box  is  ten  feet  long, 
forty  inches  high,  thirty-six  inches  wide.  Cover  the 
upper  edge  of  the  box  with  heavy  felt,  glued  down 
tight,  so  as  to  make  a  tight  cushion- joint  when  top  is 
down.  Glue  a  two-inch  wide  strip  of  felt  around  the 
small  opening  near  the  bottom  of  the  box.  When  cover 
is  put  on,  the  2x8  inch  timbers,  eleven  feet  long,  are 


96 


FUMIGATION  METHODS 


slipped  through  the  mortices  in  the  uprights,  and  are 
keyed  down  to  force  the*top  down  tight.  Nine  inches 
from  the  bottom  of  the  box  put  in  a  false  slat  bottom, 
made  in  sections,  so  it  can  be  removed  to  clean  out 
dirt  from  bottom  of  box.  The  chemicals  are  placed  in 
a  little  shallow  dish  and  put  into  the  box  through  the 
little  door,  A,  which  has  a  shutter  keyed  up  tight  to 
side  of  box. 

Another  handy  box,  devised  by  a  Canadian  nurs- 
eryman,  is  made  of  double  matched  sheathing  with 


FIG.  49 — THE  OPEN  BOX  USED  IN  SOME   MARYLAND  NURSERIES 
(ORIGINAL) 

tarred  paper  between.  The  top  is  held  tightly  against 
the  felt  padding  by  driving  the  wooden  hooks  from  an 
upright  into  a  slanting  position.  The  hooks  are  made 
of  hard  wood  pieces  1x3  inches,  cut  so  as  to  hook  over 
the  edge  of  the  lid  and  under  the  long  side  strip.  The 
rack  in  the  bottom  of  the  box  keeps  the  trees  away 
from  the  chemicals  and  insures  a  thorough  penetration 
of  the  gas.  This  box  is  shown  in  Fig.  48. 

A  plain  box,  6x3  x  2^  feet  is  very  satisfac- 
tory for  small  orders.  It  should  be  made  of  two 
thicknesses  of  common  flooring.  The  construction  is 


EQUIPMENT   FOR    FUMIGATING   NURSERY  STOCK     97 

shown  in  Figs.  49  and  50.  It  is  a  simple,  plain,  open 
box,  and  when  filled  with  young  trees,  kept  in  place 
by  a  couple  of  slats,  a,  it  is  turned  bottom  upward 
on  the  ground  and  a  little  loose  earth  is  stamped  about 
the  edges.  The  chemicals  can  be  easily  introduced  by 
tilting  the  box  slightly,  as  shown  in  Fig.  50.  It  is 
less  troublesome  than  boxes  having  lids,  and  can  be 
used  to  very  good  advantage  in  most  cases  where 
small  numbers  of  trees  are  grown. 

A  fumigatorium  is  a  house  or  room  constructed  or 


FIG.  5O— OPEN  BOX  REVERSED   READY  FOR  CHEMICALS 
(ORIGINAL) 

adapted  for  the  fumigation  of  nursery  stock  or  other 
material  with  hydrocyanic  acid  or  other  gases.  It  is 
not  necessary  in  all  instances  to  construct  a  separate 
building  for  this  purpose.  In  most  cases  where  a  nurs- 
ery has  been  established  some  years  a  shed  or  one 
corner  of  a  building,  packing-house,  or  other  enclosure, 
can  be  adapted  so  as  to  make  a  satisfactory  room  or 
house  for  fumigating  purposes.  Cover  the  frame 
inside  with  cheap  boards;  then  put  on  three-ply  cyclone 
or  rawhide  building  paper,  and  finally  the  flooring. 
In  every  case  have  a  good  smooth  surface  on  which  to 


EQUIPMENT   FOR   FUMIGATING   NURSERY  STOCK     99 

secure  the  paper.  The  flooring  can  be  joined  very 
easily  and  will  be  tight.  The  ceiling  and  floor 
should  be  constructed  in  the  same  manner.  In  some 
cases  a  good  solid  clay  floor  will  answer.  Care  should 
be  taken  to  see  that  the  house  is  absolutely  tight  at  the 


FIG.    52 — ROOM    WHERE    TREES    ARE    FUMIGATED    BY    THE 
WAGON-LOAD 

ground  surface      A  ceiling  six  to  seven  feet  in  hight 
is  most  desirable  and  economical. 

One  of  the  largest  houses  in  the  country  in  which 
nursery  stock  is  fumigated  is  shown  in  Fig.  51.  It  is 
32  x  1 6  x  8  feet  with  a  roof -pitch  of  two  feet,  and  is 
divided  into  two  large  rooms  about  15  x  14x7  feet 
and  two  smaller  rooms  4x5x7  feet.  The  flues  lead- 
ing out  at  the  top  of  the  roof  are  so  arranged  they  will 


100 


FUMIGATION   METHODS 


ventilate  either  room  by  jemoving  a  slide.  In  addition 
to  these  roof- flues  there  are  also  two  small  doors,  3  x 
2^  feet,  one  for  each  large  room,  on  the  opposite  side 
of  the  building,  which,  when  opened,  insures  quick 
ventilation. 

In   the   construction   of  this   house,  first   a   good 


FIG.    53 — DOUBLE    ROOMS    BUILT    IN    END    OF    PACKING-SHED 


strong  frame  was  built  and  covered  outside  with  one 
and  one-quarter  inch  twelve-inch  Virginia  pine  boards, 
^  x  4  inch  battens.  The  interior,  including  the  floor, 
was  lined  with  two-ply  cyclone  paper,  over  which 
four- inch  flooring  was  laid.  The  roof  was  covered 
with  heavy  roofing  paper,  tarred  and  graveled.  The 
doors  are  6%  x  3/4  feet,  made  double,  refrigerating 


EQUIPMENT   FOR   FUMIGATING  NURSERY  STOCK      IOI 

style,  and  hung  with  three  heavy  strap-iron  hinges. 
There  should  be  a  good  strong  bolt  at  top  and  bottom, 
and  a  lock  in  the  middle  of  the  door. 

Another  form,  and  very  convenient  house  for  firms 
handling  a  million  or  more  trees,  is  shown  in  Fig.  52. 
It  is  built  in  one  end  of  the  packing-shed,  and  is  16  x 


i 


FIG.    54 — SINGLE    ROOM    USED    IN    WINTER    FOR    GRAFTING 

13  x  9^  feet.  There  is  another  room  the  same  size  on 
the  opposite  side  of  the  building.  These  houses  were 
constructed  so  as  to  admit  a  wagon-load  of  trees  at  one 
time.  While  a  load  is  being  fumigated  in  one  side, 
the  other  is  being  removed  and  everything  is  in  readi- 
ness for  another  charge.  These  rooms  are  really  too 
large,  and  it  requires  a  great  deal  of  cyanide  to  fumi- 


EQUIPMENT   FOR   FUMIGATING  NURSERY  STOCK     103 

gate  space  not  occupied  by  trees.  For  example,  the 
space  occupied  by  the  wagon  must  be  considered. 
The  construction  of  this  house  is  the  same  as  the  pre- 
ceding, except  that  the  roof  is  of  corrugated  iron  and 
a  clay  floor. 

Another  type  of  hou.se  is  shown  in  Fig.  53.     Here 


F.IG.  56 — VERY  HANDY  AND  CHEAP  HOUSE  FOR  SMALL  NURSERY 

the  two  rooms  are  built  in  the  end  of  the  large  packing- 
shed.  There  are  two  doors,  same  size  as  those  open- 
ing outside,  leading  into  the  packing-shed.  The 
rooms  are  filled  with  trees,  and  when  fumigated  and 
ventilated,  by  means  of  a  large  flue  leading  out  the 
top  of  the  roof,  they  are  passed  into  the  packing-shed. 


104 


FUMIGATION   METHODS 


This  is  one  of  the  handiest  and  best-constru<5led  houses 
in  Maryland. 

A  single  room,  suitable  for  a  quarter  to  a  half  a 
million  trees,  is  shown  at  Fig.  54.  This  house  is  con- 
structed with  sliding  windows  in  addition  to  the  small 
doors.  The  flue  is  so  arranged  that  it  can  be  used  as 
a  chimney,  if  necessary,  in  winter.  In  fact,  this  is 
called  the  "  handy  house."  In  cold  weather  it  is  used 
for  grafting.  The  room  is  i3x  n  x8  feet. 

Another  single  room  of  smaller  size  is  shown  in 


FIG.    57 — OUTLINE   OF   MODEL   FUMIGATING    HOUSE.        (ORIGINAL) 


FIG.    58 — PLAN   OF    SLAT   FLOOR.       (ORIGINAL) 

Fig.  55.  It  is  a  very  handy  and  neatly  constructed 
house.  Itisi2xi4xy  feet.  It  is  sided  up  with 
first-class  tongue  and  grooved  flooring,  instead  of  or- 
dinary boards,  and  has  a  corrugated  iron  roof.  There 
is  a  small  door  in  the  opposite  end,  wdth  a  sliding 
window.  This  house  accommodates  a  firm  handling 
a  quarter  of  a  million  trees  annually. 

A  very  handy  and  economical  house  is  shown  in 


EQUIPMENT   FOR  FUMIGATING   NURSERY  STOCK     105 

Fig.  56.  It  consists  of  one  large  room,  10  x  8  x  7 
feet  and  two  smaller  rooms,  each  4x4x7  feet.  Only 
one  of  the  smaller  rooms  is  lined.  The  other  one  is 
used  as  a  storeroom,  in  which  all  chemicals  and  other 
materials  are  kept. 

One  of  the  most  convenient  houses  used  has  a  ground 
plan  of  12  x  1 6  feet.  It  is  divided  into  three  sections,  as 


FIG.    59 — GENERAL    PLAN    OF    FLOOR.       (ORIGINAL) 

follows :  one  large  room  12  x  12,  and  a  small  room  4  x 
8,  with  a  storeroom  4x4  feet.  The  floor  plan  and 
general  outline  of  this  building  are  shown  in  Figs.  57, 
58,  and  59.  It  has  a  double  floor  with  paper  between, 
and  a  space  of  one  and  one-half  feet,  as  shown  in  the 
diagram,  d  d,  above  which  there  is  a  slat  floor,  on  a 
level  with  the  bottom  of  the  door,  as  shown  at  a  and 
b.  In  the  storeroom,  e,  the  floor  is  solid.  In  the 
construction  of  this  building  the  slats  should  be  made 
in  sections,  so  they  can  be  removed.  It  will  be  found 
necessary  to  clean  the  lower  part  of  the  house  from 


FIG.    60 — WHERE    TREES    ARE    FUMIGATED    BY    THE    MILLION 


FIG.    6l — A   WELL-BUILT   SINGLE-ROOM    HOUSE   FOR    SMALL 
NURSERY 


EQUIPMENT   FOR   FUMIGATING  NURSERY  STOCK     1 07 

time  to  time,  as  more  or  less  dirt  will  rattle  through 
the  slats  upon  the  floor.  The  slats  are  used  so  that 
the  gas  can  be  generated  underneath  the  nursery  stock, 
thereby  obtaining  a  more  general  diffusion. 

The  jar  containing  the  chemicals  can  be  placed 
under  the  slats  through  the  small  doors  at  the  base, 


FIG.    62 — A    COMPLETE    FUMIGATING    HOUSE   IN    UTAH 

d  d,  and  very  often  it  is  advisable  in  a  large  room  to 
have  two  doors  of  this  character,  so  that  the  chemicals 
can  be  divided  and  the  gas  generated  on  opposite 
sides.  Good  results  are  obtained  where  this  plan  is 
followed.  The  small  doors  used  for  ventilation  pur- 
poses, c  c,  can  vary  in  size  to  meet  the  conditions. 
The  door  entering  the  storeroom  need  not  be  double, 
and  3x6  feet  is  a  convenient  size.  A  good  solid 


jZoor  *±Y***&;jt+*^ 


FIG.  63 — SECTIONAL  VIEW  OF  A  MODEL  UTAH  HOUSE 
(AFTER  MOORE) 


EQUIPMENT   FOR   FUMIGATING   NURSERY  STOCK      IOQ 

dirt  floor  will  answer,  provided  the  room  is  made  per- 
fectly tight  at  the  bottom. 

Two  other  model  houses  are  shown  in  Figs.  60  and 
61.  The  former  is  for  a  large  nursery,  while  the  latter 
is  used  for  a  smaller  concern,  handling  half  a  million 


FIG.    64 — DOUBLE    HOUSE    IN    CANADA    FOR    FUMIGATING    TREES 
ON    A    WAGON 

trees  or  less.  The  latter  is  used  for  a  storehouse  when 
not  in  use  for  fumigation. 

One  of  the  newest  fumigating  houses  in  the  north- 
west is  shown  in  Fig.  62.  It  is  10  x  14  feet.  The 
details  of  construction  are  about  the  same  as  those 
already  given.  The  ventilator  and  method  of  oper- 
ating it  is  shown  in  Fig.  63.  This  house,  complete, 
cost  about  $70. 

Of  the  many  fumigating  houses  in  use  in  Canada 


IIO  FUMIGATION   METHODS 

those  shown  in  Figs.  64  and  65  will  serve  as  examples. 
Figure  64  is  a  view  of  a  double  house.  It  has  two 
separate  compartments.  While  a  load  of  trees  is  being 
fumigated  in  one  compartment,  ventilation  is  taking 
place  in  the  other.  It  has  two  thicknesses  of  lumber, 
one  matched,  tongue  and  grooved,  the  other  either  the 


FIG.    65 — CANADIAN    FUMIGATING   HOUSE  AT   THE   ONTARIO 
AGRICULTURAL    COLLEGE 

same  or  cover-siding  well-matched,  and  two  thicknesses 
of  paper  between.  The  doors  are  the  same  and  padded 
all  around. 

Figure  65  shows  the  fumigation  house  at  the  Agri- 
cultural College  at  Guelph,  Canada.  It  is  substan- 
tially built,  dressed  lumber  being  used  in  its  construc- 
tion. Its  size  is  10x8x7^  feet.  It  contains  600 
cubic  feet.  The  frame,  of  2  x  4  inch  scantling,  has  two 


EQUIPMENT   FOR   FUMIGATING  NURSERY  STOCK    III 

thicknesses  of  lumber,  both  matched,  tongue  and 
grooved,  and  firmly  nailed  on  the  outside,  with  a 
thickness  of  tarred  paper  between.  Besides,  the  seams 
on  the  outside  are  covered  with  strips.  The  doors  are 
of  the  refrigerator  style,  and  the  casements  are  padded 
with  soft  felting.  Large  wooden  buttons  are  placed 
on  the  outside,  around  the  edge  of  the  door,  to  force  it 
closely  into  the  padded  casement.  The  roof  has  a 
thickness  of  matched  boards,  then  a  thickness  of 
tarred  paper,  then  shingles.  The  cost  of  the  complete 
building  was  a  trifle  over  $20. 


CHAPTER  XII 

CONSTRUCTION  OF  VENTILATORS  AND  FLOORS 

O""YNK  of  the  Canadian  houses  has  a  unique  venti- 
I     lator.     Just  before  the  gas  is  generated  the 
hinged    trap    is   pulled    up    tightly   against 
the  felt,  and  the  rope  fastened  to  a  cleat  on 
the  side  of  the  house,  as  shown  in  Fig.  66.    Before  the 


FIG.  66 — METHOD  OF  VENTILATING  A  FUMIGATING  HOUSE 
(AFTER  LOCHHEAD) 

door  is  opened  the  rope  is  loosened,  and  the  weight 
brings  down  the  trap  and  allows  the  gas  to  escape.  A 
ventilator  of  this  kind  having  the  trap  opening  into 
the  inside  is  protected  from  the  weather,  and  is  not 
subject  to  the  troublesome  warping  of  exposed  cap 
ventilators. 

An  Ohio  arrangement. — In  his  practical  work  in 

112 


CONSTRUCTION   OF   VENTILATORS   AND   FLOORS    113 

Ohio,  Prof.  F.  M.  Webster  has  fo^nd  slats  raised 
eight  inches  or  a  foot  from  the  ground  preferable  to 
the  ground  floor.  Where  it  is  intended  to  drive 
wagons  into  the  house  the  ground  floor  will  answer 
all  purposes.  With  a  slat  floor  the  gas  is  generated 
beneath,  and  spreads  almost  instantly  throughout  the 
space  between  the  ground  and  the  slats,  passes  up- 


FIG.    67 — DIAGRAM    OF    GENERATOR    AND    SECTIONAL    VIEW 
OF    FUMIGATORIUM.       (AFTER   WEBSTER) 

ward  through  the  trees,  and  promptly  reaches  every 
part  of  the  apartment. 

The  generator,  shown  in  Fig.  67,  consists  of  an 
earthen  jar  of  the  requisite  capacity,  a,  fixed  to  the 
end  of  a  plank,  b,  and  just  in  front  and  between  two 
posts,  cct  through  which  passes  a  roller,  dt  and  to 
this  last  is  fixed  a  pan,  £,  with  back  and  sides  but 
no  front,  one  end  of  the  roller  projecting  beyond  the 
post  with  a  small  iron  bar  or  heavy  wire,  /,  passing 
through  it,  and  being  fixed  and  bent  at  either  end,  the 
whole  having  much  the  appearance  of  a  windlass  with 
pan,  e,  added.  The  sulphuric  acid  and  water  are 


FUMIGATION   METHODS 


placed  in  the  jar,  and  the  potassium  cyanide  in  pan 
above,  and  the  plank  pushed  down  a  slight  incline,  as 
seen  in  the  figure,  over  which  a  cleat,  g,  is  fastened, 
which  catches  the  wire  or  rod,/,  and  thus  dumps  the 
pan,  e,  throwing  the  contents  into  the  jar,  at  there- 
by completing  the  mixture  and  generating  the  gas; 
and,  as  a  drop-door  closes  as  soon  as  the  plank  is 


FIG.  68  —  LOWER  PORTION  OF  FUMIGATORIUM,  SHOWING  SLAT 

FLOOR,  IN  CROSS-SECTION,  AND  GENERATING  APPARATUS 

(AFTER  SANDERSON) 

pushed  down  the  incline,  there  is  no  chance  of  the 
operator  breathing  the  fumes.  The  arrangement  is 
simple,  and  any  one  at  all  handy  with  tools  can  easily 
construct  the  whole  apparatus. 

The  Delaware  method. — As  a  result  of  the  splendid 
work  of  Professors  Sanderson  and  Penny,  of  the 
Delaware  Experiment  Station,  many  obscure  points 
about  the  diffusion  of  the  gas  have  been  cleared 
up.  Their  experiments  point  to  the  utility  of  a  slat 
floor.  As  a  modification  of  the  ordinary  slat  floor,  to 


CONSTRUCTION  OF  VENTILATORS  AND   FLOORS    115 

secure  better  diffusion,  an  arrangement  of  the  floor 
and  generator,  as  shown  in  Fig.  68,  is  recommended. 
This  provides  for  a  slat  floor,  underneath  which  run 
smooth  wooden  tubes,  three  inches  in  diameter,  along 
the  diagonals  of  the  room  and  opening  into  a  hood 
placed  at  the  center  covering  the  generator.  These 
tubes,  extending  from  the  center,  two-thirds  of  the 


FIG.  69 — GENERATOR  AND  DETAILS  OF  HANDLING  IT 
(AFTER  SANDERSON) 

distance  to  the  corner,  are  open  at  the  ends,  and  one- 
third  from  the  center,  affording  eight  openings  for  the 
escape  of  the  gas. 

The  bag  of  cyanide  is  placed  on  a  shelf  and  the 
generator  in  the  box,  A,  at  the  end  of  the  sliding 
board,  B.  This  board  is  pushed  down  the  incline, 
C,  and  when  under  the  board  the  outer  end  is  pushed 
down  and  held  in  place  by  a  sliding  door.  The 
shelf  upon  which  the  cyanide  is  placed  rests  on  a 
pivot,  as  shown  in  Fig.  69  at  D.  Projecting  upward 
from  it  is  a  rod,  E,  forming  a  trap.  When  the  box  is 


Il6  FUMIGATION   METHODS 

thrown  up  beneath  the  hood  the  shelf  is  tipped  and 
the  cyanide  dumped  info  the  generator.  This  device 
is  simple  and  cheap. 

A  good  Western  idea. — A  Western  firm  has  a 
novel  and  practical  way  of  making  an  open  floor  and 
generating  the  gas  underneath.  They  say  :  ' '  Our 
fumigating  house  is  15x20x10  feet.  The  walls  are 
double,  of  one-inch  plank,  the  first  course  being  put 
on  lengthways  of  building,  then  common  building 
paper,  tarred  after  being  put  on.  The  second  course 
of  plank  is  put  on  up  and  down.  This  course  is  on 
the  outside  ;  roof  made  the  same  way ;  doors  simi- 
larly made,  are  double,  and  take  up  one  end  of  the 
building.  After  the  building  was  completed,  we 
banked  up  around  the  bottom  about  a  foot  with  dirt ; 
then  we  excavated  about  a  foot  and  a  half  deep,  one 
foot  from  the  bottom  of  the  walls.  For  instance,  if 
the  room  was  10x20  feet,  the  excavation  would  be 
9x19  feet,  surface  measure.  Over  this  excavation  is 
laid  three  2x4  inch  joists,  just  enough  to  hold  the 
stock  which  is  put  in  for  fumigating.  Across  these 
joists  lay  two  or  three  1 2-inch  planks,  loose.  This 
completes  the  house. 

*  'An  opening  or  flume  is  made  under  the  wall  about 
one  foot  deep  and  eighteen  inches  wide.  The  end 
extending  into  the  inside  of  the  building  is  open,  and 
extends  just  far  enough  to  let  the  gas  into  the  exca- 
vation under  the  trees.  The  outer  end  extends  out 
far  enough  to  give  the  operator  ample  room  to  insert 
the  vessel  containing  the  chemicals.  The  outer  aper- 
ture is  covered  with  a  trap-door.  The  vessel  with  the 
acid  and  water  is  set  in  the  flume,  trap- door  open,  and 


CONSTRUCTION  OF  VENTILATORS  AND   FLOORS     117 

the  cyanide  dropped  in.  The  trap-door  is  closed 
quickly  and  is  covered  immediately  with  a  piece  of 
cloth  (blanket  is  best),  and  dirt  hurriedly  thrown 
over  the  whole  business.  This  prevents  any  of  the 
gas  from  escaping,  and  makes  the  building  absolutely 
air-tight,  which  is  necessary.  The  gas  fills  the  exca- 
vation and  rises  through  the  loose  floor,  permeating 
through  the  trees,  filling  the  entire  inside  of  the 
house.  In  our  building  we  treat  about  five  thousand 
trees  at  a  time.  For  fall  deliveries  we  treat  the  stock 
as  it  comes  from  the  field  to  the  packing-ground.  For 
spring  delivery  we  treat  them  as  we  take  them  from 
the  healing  grounds  to  the  packing-grounds.  The 
cost  of  our  building  did  not  exceed  $50  complete. ' ' 


CHAPTER  XIII 
PRACTICAL  HINTS  TO  NURSERYMEN 

T!HK  amounts  of  chemicals  necessary  for  a  room 
i  are  estimated  in  terms  of  cyanide  per  cubic 
foot  of  space  enclosed.  For  example,  let  us 
suppose  a  room  contains  564  cubic  feet.  We 
use  0.25  (twenty-five  hundredths)  gramme  of  cyanide 
for  each  cubic  foot.  We  therefore  multiply  564  by 
0.25.  Thus,  564  X  0.25  =  141.00  grammes  of  cyanide. 
To  reduce  this  to  ounces  we  divided  141.00  by  28.35, 
as  there  are  28.35  grammes  in  an  ounce.  Thus, 
141.00  -=-  28.35  =  5  ounces  (a  fraction  less),  the  amount 
of  cyanide  needed  for  the  house.  The  other  chemicals 
are  easily  determined,  as  a  half  more  acid,  liquid  meas- 
ure, than  cyanide,  and  a  half  more  water  than  acid 
are  used.  Thus,  the  room  needs  5  ounces  cyanide  (by 
weight),  7^  ounces  acid  (liquid  measure),  and  n^ 
ounces  (liquid  measure)  of  water. 

As  a  rule,  we  discard  any  fraction  less  than  a  half. 
In  this  case,  therefore,  we  would  use  5  ounces  of 
cyanide,  7^2  ounces  of  acid,  and  n  ounces  of  water. 
The  cost  of  chemicals  to  fumigate  this  room,  full  of 
trees,  would  be  about  1 1  cents.  The  amount  of  cya- 
nide needed  for  any  room  can  be  determined  in  the 
same  manner.  First,  see  to  it  that  the  cubic  contents 
of  the  enclosure  has  been  accurately  computed,  then 
118 


PRACTICAL  HINTS  TO   NURSERYMEN  119 

multiply  by  0.25  (twenty-five  hundredths)  and  divide 
by  28.35,  as  indicated  above,  and  you  will  obtain  the 
correct  amount  in  ounces.  Always  bear  in  mind  that 
fumigation  will  admit  of  no  guesswork,  as  success 
depends  on  accuracy. 

Low-grade  stock,  as  indicated  in  Chapter  III. ,  should 
not  be  fumigated  with  the  0.25  gramme  formula.  The 
o.i  6  or  o.i  8  formula  should  be  used  for  June  budded 
peach  or  plum,  low  grade  peach  and  plum,  known 
as  whips,  and  for  scions,  buds,  grafts,  etc.  In  using 
this  formula,  the  cubic  contents  of  an  enclosure  should 
be  multiplied  by  o.  16  or  o.  18,  as  the  case  may  be,  and 
reduced  as  above  to  ounces. 

Cost  of  nursery  stock  fumigation. — It  is  difficult  to 
ascertain  the  exact  cost  for  fumigating  young  trees 
per  thousand.  The  conditions  under  which  the  trees 
are  grown  and  handled  in  most  States  varies  consider- 
ably. In  most  cases,  nurserymen  who  have  had  much 
experience  along  this  line  have  found  that  the  ordi- 
nary first-class  grade  of  fruit  trees  can  be  fumigated  at 
a  cost  not  to  exceed  twenty-five  cents  per  thousand 
trees.  This  amount  includes  the  chemicals  and  extra 
labor  in  handling.  However,  the  cost  of  the  fumiga- 
ting house  or  box  is  not  taken  into  consideration.  In 
many  cases  where  a  room  can  be  filled  with  trees  the 
cost  of  fumigation  can  be  reduced  from  ten  to  fifteen 
cents  per  thousand  trees,  depending  upon  the  grade 
and  kind.  It  is  often  necessary  to  fumigate  a  small 
bundle  of  trees  in  a  large  room  or  enclosure.  In  such 
a  case,  the  quantity  of  chemicals  necessary  to  fill  the 


120  FUMIGATION   METHODS 

room  is  the  same  as  if  Jhe  entire  enclosure  was  filled ; 
therefore,  the  cost  would  be  somewhat  increased. 

Small  room  a  necessity. — Whatever  may  be  the 
size  of  the  nursery,  a  small  room,  say  4x5x7  feet,  is 
a  necessity.  Very  often  a  small  order  or  a  few  trees 
to  complete  a  big  order  are  needed  quickly.  It  would 
be  poor  economy  to  use  eighteen  ounces  of  cyanide, 
costing  about  forty  cents,  to  fumigate  a  handful  of 
trees  in  a  large  room,  when  one  ounce,  costing  less  than 
two  and  one-half  cents,  in  a  small  room  would  answer 
the  same  purpose.  It  is  not  desirable,  in  most  cases, 
to  mix  up  small  orders  with  car-load  lots,  and  in  most 
nurseries  a  small  room  will  be  found  in  almost  con- 
stant use.  The  kind,  shape,  size,  and  location  of  the 
fumigating  house  rests  entirely  with  the  individual, 
and  he  must  be  the  judge  as  to  what  is  best  suited  for 
his  purposes.  One  thing  must  be  remembered  at  all 
times,  whatever  may  be  constructed,  and  that  is,  it 
must  be  gas-proof. 

Preparation  of  trees. — The  house  having  been  con- 
structed, the  next  step  is  the  proper  preparation  of  the 
trees  for  treatment.  In  the  first  place,  care  should  be 
taken  that  the  trees  are  thoroughly  matured  and  dor- 
mant before  they  are  dug  and  passed  into  the  fumi- 
gating house.  Nurserymen  should  heed  carefully  the 
cautions  cited  in  Chapter  III.  Well-matured  nursery 
stock  should  be  dug  in  the  customary  way,  tied  in 
loose  bundles,  brought  to  the  fumigatorium,  and  piled 
loosely,  not  packed,  upon  the  floor,  with  the  roots 
toward  the  walls  and  tops  overlapping.  The  trees 
should  be  as  dry  as  possible.  They  may  be  damp  or 


PRACTICAL   HINTS  TO   NURSERYMEN  121 

moist,  but  should  not  be  drenching  wet.  Where  only 
a  few  trees  are  fumigated,  they  are  usually  stood  on 
the  floor  in  bunches.  When  the  desired  number  has 
been  placed  in  the  room,  and  the  ventilators  have  been 
closed,  they  are  ready  for  the  gas.  The  chemicals  are 
then  prepared  and  placed,  after  which  the  doors  are 
closed,  and  left  the  desired  length  of  time.  A  half- 
hour  is  the  minimum  limit,  but  thoroughly  matured 
dormant  trees  are  not  injured  in  the  least  if  left  an 
hour.  The  chemicals  should  be  prepared  and  used 
strictly  in  accordance  with  the  directions  given  in 
Chapter  II. 

Other  materials  needed. — A  pickle  jar  or  china  dish 
holding  from  two  to  four  quarts  is  best  adapted  for 
holding  chemicals  for  the  generation  of  the  gas  in 
ordinary  houses.  Sometimes  a  larger  vessel,  such  as  a 
snuff- jar,  is  needed.  A  liberal  supply  of  small  manila- 
paper  bags  holding  a  pound  or  more  are  necessary. 
Where  the  amount  of  cyanide  needed  is  known,  it  can 
be  weighed,  placed  in  manila  bags,  and  kept  in  an 
air-tight  can  or  other  enclosure  ready  for  use.  Care 
should  be  taken  not  to  weigh  too  much  cyanide  at  a 
time,  as  the  bags  become  saturated  with  moisture  if 
long  exposed  to  the  air.  It  is  best  to  weigh  the  cyanide 
at  night  or  early  in  the  morning,  or  even  during  the 
noon  hour,  rather  than  have  it  standing  around  for 
several  days.  A  glass  beaker,  holding  from  a  pint  to 
a  quart,  with  a  graduated  scale  on  the  side  in  ounces, 
will  be  required  for  the  acid  and  water.  A  supply  of 
acid  should  be  kept  in  a  carboy  or  other  vessel.  It 
should  be  drawn  in  an  ordinary  glass,  china,  or  agate 
pitcher,  as  needed.  For  immediate  use,  a  supply  of 


122  FUMIGATION   METHODS 

water,  together  with  a  cup  or  glass  for  dipping,  should 
be  kept  close  at  hand. 

Cellars  and  cars. — It  is  not  desirable  to  attempt  to 
fumigate  trees  after  they  are  packed  in  cellars  or  cars. 
In  some  cases  serious  injury  has  been  done  when  trees 
were  fumigated  in  freight-cars  after  being  packed. 
As  a  rule,  the  roots  are  so  closely  packed  with  moss 
and  other  materials  when  put  in  cars  it  is  difficult 
for  the  gas  to  get  to  them.  It  is  practically  im- 
possible to  properly  ventilate  the  car  afterward,  and 
more  or  less  gas  is  left.  The  only  proper  place  to 
treat  trees  is  in  the  fumigatorium. 

Canvas  over  wagon. — An  enterprising  nursery  firm 
in  Utah  uses  a  canvas  sheet  over  a  wagon  loaded  with 
trees,  in  addition  to  the  use  of  a  house.  They  give  the 
following  description  of  house  and  method  of  handling 
tent:  "  For  a  number  of  years  we  used  a  small  room 
about  12x12  feet.  Finding  this  too  slow  a  process, 
we  put  up  a  building  22  x  56  and  9  feet  high.  The 
roof  and  entire  building  is  made  with  two  thicknesses 
of  i  x  12  feet  boards,  with  building  paper  between, 
which  makes  it  very  tight.  As  this  was  rather  large 
for  ordinary  use,  we  made  a  partition,  making  the 
smaller  room  22  x  20.  This  latter  room  we  use  mostly 
when  we  store  our  stock  inside  to  be  treated. 

<l  We  think,  however,  by  far  the  better  and  more 
economical  method  is  to  do  the  fumigating  on  the  wagon 
at  the  time  stock  is  dug  and  hauled  in.  This  is  done 
by  using  a  canvas  sufficiently  large  to  cover  the  entire 
load,  with  a  few  feet  of  margin,  which  should  be  spread 
on  the  ground  and  weighted  down  to  keep  the  fumes 


PRACTICAL   HINTS  TO   NURSERYMEN  123 

from  escaping.  In  order  to  lower  wagon,  trenches 
should  be  made  to  allow  wheels  to  drop  down.  Our 
canvas  is  32  x  38  feet.  This  is  a  large  sheet  and  un- 
wieldly  to  handle  unless  parties  know  how  it  should 
be  done.  Our  method  is  to  place  the  sheet  behind  the 
wagon,  doubling  the  front  end  back  over  the  other. 
To  the  corners  of  the  top  'canvas  fasten  poles  long 
enough  to  clear  the  load.  Fasten  lines  at  ends  of 
poles,  and  when  ready  to  raise  have  men  pull  the 
ropes.  The  air  will  be  of  great  assistance,  and  if 
quickly  done  the  canvas  will  sail  over  without  friction. 
Our  experience  has  been  that  hydrocyanic  acid  gas 
properly  applied  is  certain  death  to  all  insect  life. '  * 

Points  to  remember. — i.  Never  let  a  tree  go  out  of 
the  nursery  unless  it  has  been  fumigated. 

2.  Never  fumigate  a  tree  on  which  there  is  known 
to  be  a  San  Jose"   scale.     The   furnace,  and  not  the 
fumigating  house,  is  the  place  for  such  trees.     A  dead 
scale  on  the  tree  is  just  as  demoralizing  to  the  nursery 
business  as  a  live  one  if  seen  by  the  buyer. 

3.  Never  use  the  gas  stronger  than  0.25  gramme 
cyanide  per  cubic  foot  on  any  kind  of  nursery  stock. 

4.  Never  leave  the  trees  exposed  to  the  gas  longer 
than  an  hour.     Thirty  to  forty-five  minutes  is  suffi- 
cient. 

5.  Never  fumigate  trees,  especially  peach,  a  second 
time. 

6.  Never  fumigate  trees  in  a  car,  box,  or  cellar  after 
they  are  packed. 

7.  Never  fumigate  trees  when  they  are  drenching 
wet.     They  may  be  moist,  even  quite  damp. 


124  FUMIGATION   METHODS 

8.  Never  puddle  the  roots  of  trees  before  they  are 
fumigated. 

9.  Never   fumigate    cedars    and   evergreen   trees, 
unless  there  is  some  special  reason  for  it. 

10.  Never  fumigate  trees  until  the   wood  is  well 
matured  and  the  buds  are  thoroughly  dormant. 

1 1 .  Never  fumigate  trees  after  the  buds  have  begun 
to  open  in  the  spring. 

12.  Never   fumigate  June  buds  and  peach  under 
three  feet  with  gas  stronger  than  o.  18  gramme  cyanide 
per  cubic  foot.     Better  use  o.  16  gramme. 

13.  Never  fumigate  buds,  grafts,  or  scions  with  gas 
stronger  than  o.  16  gramme. 

14.  Never  leave  the  cyanide  can  where   children 
can  reach  it. 

15.  Never  let  the  cyanide  can  be  without  a  con- 
spicuous label,  "  Poison." 

1 6.  Never  leave  the  cyanide  exposed  to  air.     It 
will  absorb  moisture  and  be  ruined. 

17.  Never  take  a  bag  of  cyanide  out  of  a  can 
unless  you  are  all  ready  to  use  it. 

1 8.  Never  leave  the  door  of  the  fumigating  room 
open  a  moment  after  the  cyanide  has  been  dropped  in 
the  jar. 

19.  Never  allow  a  person  to  go  near  or  open  the 
door  when  fumigating  trees  or  anything  else. 

20.  Never  allow  anybody  to  enter  a  room  under 
ten  to  fifteen  minutes  after  the  door  and  ventilators 
are  open. 

21.  Never  empty   residue  of   jar   where   children 
would  play  in  it. 

22.  Never  allow  residue  to  remain  long  in  the  jar. 


PRACTICAL   HINTS   TO   NURSERYMEN  125 

22.  Never  put  a  new  charge  in  a  jar  containing  the 
old  residue. 

24.  Never  put  sulphuric  acid  in  tin  or  iron  vessels  ; 
it  will  eat  them  up.     Always  use  glass,  earthenware, 
agate,  or  wooden  vessels. 

25.  Never  lose  an  opportunity  to  caution  persons 
about  the  danger  attending  the  inhalation  of  this  gas. 


CHAPTER  XIV 
GREENHOUSE    AND    COLD     FRAME     FUMIGATION 

T""|HE  greenhouse  problem  in  reference  to  insects 
has  been  one  of  considerable  importance. 
Early  in  1894  Dr-  Albert  F.  Woods,  assisted 
by  Mr.  Dorsett,  as  noted  in  Chapter  III., 
began  a  series  of  experiments  under  glass  with  this 
gas.  They  found  that  plants  were  less  injured  by  a 
short  exposure  to  a  relatively  large  amount  of  gas 
than  they  were  by  a  long  exposure  of  a  relatively 
small  amount.  It  was  also  shown  that  the  stronger 
dose  a  short  time  was  most  destructive  to  the  insects 
affecting  the  plants.  In  these  experiments  they 
showed  that  different  species  and  varieties  of  plants 
varied  remarkably  in  their  power  to  withstand  the  gas, 
depending  upon  the  open  or  closed  condition  of  the 
breathing  pores  of  the  leaf,  the  cell  contents,  and  tem- 
perature of  the  inclosure.  The  plants  fumigated  were 
ferns,  coleus,  double  English  violets,  single  violets, 
roses,  carnations,,  grapes,  tomatoes,  and  cucumbers. 

The  amount  of  cyanide  used  per  cubic  foot  of  space 
inclosed  varied  from  0.075  gramme  to  0.15  gramme. 
For  instance,  ferns,  infested  with  a  scale  insect,  sim- 
ilar to  the  scurfy  scale  on  apple,  were  fumigated  at 
night  with  0.075  gramme  98  per  cent,  cyanide  for 
twenty  minutes  without  injuring  the  most  delicate 
fronds,  at  the  same  time  destroying  all  the  insects.  In 
case  of  coleus,  infested  with  mealy  bug,  in  a  very 

126 


GREENHOUSE   AND   COLD   FRAME   FUMIGATION    127 

large  house  (15,587  cubic  feet),  one-tenth  (o.  10) 
gramme  cyanide  was  used.  In  case  of  the  double 
English  violets,  infested  with  plant-lice,  slugs,  milli- 
pedes, leaf-eating  larvae,  cutworms,  red  spiders,  etc., 
fifteen  hundredths  (0.15)  gramme  was  used,  and  ex- 
posed twenty  minutes.  All  the  insects  were  destroyed, 
excepting  a  few  red  spiders,  and  even  these  were  kept 
down  by  frequent  fumigation. 

EffeEls  on  foliage. — The  foliage  of  single  violets, 
like  California,  Princess  of  Wales,  and  the  like,  is  some- 
times slightly  injured  with  the  stronger  dose  of  0.15; 
a  weaker  amount,  one-tenth  (o.  10)  gramme  should  be 
used  for  these  single  varieties.  Roses,  especially  the 
younger  growths,  are  very  sensitive,  and  slight  injury 
has  been  noticed  even  where  the  smallest  dose  (0.075 
gramme)  was  used.  Carnations  will  stand  one- tenth 
(o.  10)  gramme  for  fifteen  minutes;  but  more  careful 
experiments  are  needed  before  the  gas  is  generally 
recommended  for  either  carnations  or  chrysanthe- 
mums. 

Grapes,  under  glass,  in  New  Zealand,  have  been 
fumigated  at  the  rate  of  nine-hundredths  (0.09) 
gramme  over  night,  infested  with  mealy  bugs,  with 
good  results.  It  has  also  been  used  successfully  by 
Dr.  J.  Fisher  on  tomatoes  infested  with  the  white  fly. 
He  used  one  ounce  cyanide  (28.35  grammes)  for 
1,000  cubic  feet,  and  left  the  plants  exposed  over 
night  without  injury.  The  writer  fumigated  a  green- 
house in  Maryland  in  which  cucumbers  were  growing 
and  badly  infested  with  the  melon  louse  (Aphis 
gossypii).  The  house  was  filled  with  gas  at  sundown, 
using  fifteen-hundredths  (0.15)  gramme  of  cyanide  per 


128  FUMIGATION   METHODS 

cubic  foot,  and  left  until  morning.  The  lice  were  all 
destroyed,  and  there  was  no  perceptible  injury  to  the 
plants.  Indian  corn,  from  ten  to  twelve  inches  high  in 
pots  standing  in  one  end  of  the  house  for  experimental 
purposes,  was  destroyed. 

Preparation  of  the  house. — The  very  poisonous 
nature  of  the  gas  must  be  considered.  The  cautions 
cited  in  Chapters  III.  and  IV.  should  be  heeded.  The 
house  should  be  made  as  nearly  tight  as  possible  under 
ordinary  circumstances.  The  ventilators  should  be 
arranged  so  several  of  them  can  be  opened  from  the 
outside.  Plants  that  will  not  stand  the  stronger  doses 
of  gas,  if  in  pots,  should  be  removed.  The  room 
should  not  be  fumigated  immediately  after  the  plants 
have  been  sprinkled  or  watered.  The  floor  of  the 
house  should  not  be  drenching  wet,  although  it  may 
be  damp. 

After  estimating  the  cubic  contents  of  the  house, 
and  the  amount  of  cyanide  is  determined,  the  quantity 
needed  can  be  figured  out  according  to  the  directions 
given  in  Chapter  XIII.  for  nursery  stock.  Care 
should  be  taken,  however,  to  multiply  the  number  of 
cubic  feet  by  the  exact  fraction  of  a  gramme.  For 
instance,  0.25  gramme  cyanide  per  cubic  foot  is  used 
for  well-matured  and  dormant  nursery  stock,  and  0.20 
gramme  for  orchard  trees  out-doors;  but  no  such  doses 
are  used  in  greenhouses.  Very  good  results  have 
been  obtained  where  0.15  gramme  cyanide  per  cubic 
foot  has  been  used  in  greenhouses  and  cold  frames  for 
the  violet  aphis.  For  other  insects  and  plants  the 
amount  of  cyanide  varies,  as  indicated  above. 


130  FUMIGATION   METHODS 

How  to  prepare  the  jar. — The  chemicals  should  be 
prepared  strictly  in  accordance  with  directions  given 
in  Chapter  II.  An  earthenware  crock  or  jar  will  be 
needed,  the  size  of  the  vessel  depending  upon  the 
capacity  of  the  enclosure.  The  number  of  vessels 
needed  will  depend  upon  the  size  of  the  house  to  be 
fumigated.  In  a  small-sized  house  single  jars  may  be 
sufficient,  but  as  a  rule  it  is  desirable  to  use  two  or 
more  crocks  or  vessels.  After  the  acid  and  water  have 
been  mixed  and  placed  in  the  vessels,  the  cyanide, 
which  has  been  previously  weighed  and  wrapped  in 
strong  manila  paper  bags,  is  suspended  over  the  crocks, 
as  shown  in  the  illustration. 

Several  hooks  or  screw-eyes  can  be  used  conve- 
niently to  carry  the  string  from  the  door  to  the  vessels. 
There  should  be  as  many  lines  of  string  as  there  are 
vessels,  each  one  leading  to  the  door  or  outside  open- 
ing, as  shown  in  Fig.  70.  If  the  building  requires 
four  pounds  of  cyanide  and  two  jars  are  to  be  used,  it 
is  desirable  to  divide  the  cyanide  into  equal  parts. 
Before  the  acid  and  water  are  placed  in  the  jars,  it  is 
well  to  tie  the  bags  of  cyanide  to  the  cords  and  see 
whether  or  not  they  work  satisfactorily.  Care  should 
be  taken  to  see  that  the  bags  when  lowered  will  go 
into  the  crocks,  and  thus  into  the  chemicals,  without 
difficulty. 

At  times  it  is  necessary  to  use  some  protection 
around  the  jars  to  prevent  the  injury  of  the  foliage  in 
case  plants  are  too  near.  A  section  cut  from  a  roll  of 
building  paper  can  be  used  to  good  advantage,  as  the 
paper  rolls  in  a  tube  and  can  be  placed  around  the 
vessel,  thus  keeping  the  acid  and  water  from  spattering 


132  FUMIGATION   METHODS 

on  the  surrounding  plants.  Paper  used  for  this  pur- 
pose can  be  rolled  together,  laid  away,  and  is  ready  for 
future  use.  When  everything  is  in  readiness,  doors  and 
ventilators  should  be  closed,  and  the  cyanide  lowered 
into  the  vessels  by  loosening  the  strings.  The  gas  is 
given  off  almost  immediately  and  a  small  quantity  will 
leak  out  of  the  house;  but  if  the  room  is  reasonably 
tight  the  greater  portion  of  it  will  be  kept  within  for 
a  time  sufficient  to  destroy  the  pests.  When  the 
proper  time  has  elapsed,  varying,  of  course,  for  different 
plants,  the  ventilators  should  be  opened  from  the  out- 
side, so  that  the  gas  can  escape  as  rapidly  as  possible. 
After  free  circulation  is  obtained  by  opening  the  doors 
and  ventilators,  all  traces  of  the  gas  will  have  dis- 
appeared from  the  house  in  from  thirty  to  forty 
minutes.  The  house  can  then  be  closed  if  desired. 
The  residue  left  in  the  jars  should  be  emptied,  as 
previously  described. 

Boxes  for  fumigating  small  plants. — Where  it  is 
desirable  to  fumigate  several  hundred  small  plants, 
small  boxes,  such  as  described  in  Chapter  XI. ,  can  be 
used  to  good  advantage.  In  most  cases  a  special  box, 
such  as  shown  in  Figs.  47  and  48,  is  desirable.  The 
box  should  be  as  nearly  air-tight  as  possible,  with  a 
removable  cover  or  trap-door  which  can  be  quickly 
closed.  A  special  box,  shown  in  Fig.  71,  was  con- 
structed and  used  by  Prof.  K.  D.  Sanderson  for  the 
fumigation  of  small  plants.  Small  wire  or  slatted  trays 
can  be  used  to  good  advantage  for  the  fumigation  of 
cuttings,  such  as  coleus  and  various  other  plants. 
Potted  plants  can  be  fumigated  in  the  same  box  if 
necessary. 


GREENHOUSE   AND   COLD   FRAME   FUMIGATION    133 

A  plain  wooden  box,  such  as  is  shown  in  Figs.  49 
and  50,  or  even  a  small  Kmory  fumigator,  as  seen  in 
Figs.  33  or  36,  will  be  found  very  useful  to  florists 
and  gardeners  in  any  greenhouse  or  nursery  grounds. 
This  box  can  be  used  for  the  fumigation  of  small 
shrubs  and  plants  on  lawns,  in  gardens,  and  various 
other  places  where  it  is  desirable  to  fumigate  them 
without  taking  them  up.  The  box  may  be  used  in 
the  daytime  if  the  work  is  done  in  a  cool  place. 
Some  florists  and  nurserymen  use  small  boxes  in  their 
packing-houses  and  cellars  where  the  temperature  is 
constant.  Care  must  be  taken,  however,  where  the 
gas  is  generated  and  released  in  such  places,  to  see 
that  proper  ventilation  is  secured  to  carry  away  the 
poisonous  fumes  when  released  from  the  box.  Nurs- 
erymen handling  ornamental  plants  can  use  their 
fumigating  houses  for  the  treatment  of  various  shrubs. 
Some  florists  have  found  that  a  small  greenhouse  con- 
taining 1,000  feet  or  less  is  more  reliable  than  a  box. 
There  is  less  danger  of  injury  to  the  foliage  under 
such  conditions. 

Experience  with  various  plants. — Although  a  large 
number  of  greenhouse  plants  have  been  fumigated, 
there  is  yet  room  for  much  careful  experimental  work. 
The  following  list  of  plants,  given  by  Dr.  Woods, 
have  been  fumigated. 

Ferns. — For  Davallia  mooreana,  infested  with  a 
scale  insect  {Chionaspis  sp.),  0.075  gramme  of  98  per 
cent,  potassium  cyanide  should  be  used  for  each  cubic 
foot  of  space  to  be  fumigated,  not  deducting  the  space 
occupied  by  the  plants.  length  of  exposure,  twenty 
minutes. 


134  FUMIGATION   METHODS 

One  hundred  and  fifty  to  two  hundred  plants  with 
fronds  in  all  stages  of  "development  have  been  thus 
treated  two  or  three  times  each  year  for  the  past  four 
years  with  no  injury  to  the  plants  and  almost  complete 
destruction  of  the  insect.  They  were  treated  fifty  at 
a  time  in  a  fumigating  box. 

Adiantum  cuneatum  and  A.  ballii  have  been  tried 
on  a  small  scale  and  were  not  injured  by  the  treatment. 

Coleus. — Golden  Bedder,  Verschaffeltii,  Shy  lock, 
and  others;  24,000  plants  in  pots,  badly  infested  with 
the  white-tailed  mealy  bug,  Orthezia  insignis.  The 
house  contained  15,587  cubic  feet  of  space.  Treated 
at  the  rate  of  one-tenth  of  a  gramme  of  98  per  cent, 
cyanide  of  potash  per  cubic  foot  of  space  for  twenty 
minutes,  one  hour  after  dark.  Orthezia  all  killed  and 
plants  not  injured  in  the  least.  All  other  means  of 
destroying  the  Orthezia  had  been  tried  without  effect. 
Large  numbers  of  the  common  mealy  bug  were  also 
killed  by  this  treatment;  but  it  was  not  nearly  so 
effective  as  for  the  white-tailed  mealy  bug.  All  coleus 
cuttings  made  by  the  United  States  Propagating  Gar- 
dens for  the  past  few  years  have  been  fumigated  before 
being  prepared  for  the  cutting  bed. 

Double  English  violets. — Marie  Louise,  Lady  Camp- 
bell, and  others.  For  plant-lice  and  general  fumiga- 
tion fifteen-hundredths  of  a  gramme  of  98  per  cent, 
cyanide  of  potassium  for  each  cubic  foot  of  space  is 
required.  The  exposure,  if  made  according  to  direc- 
tions, will  not  hurt  the  plants  in  any  stage  of  growth. 
The  gas  has  been  used  on  a  large  scale  in  fumigating 
violets  for  the  past  three  years  with  the  greatest  sue- 


GREENHOUSE   AND   COLD   FRAME   FUMIGATION    135 

cess,  only  a  few  treatments  during  the  season  being 
required.  Leaf-eating  larvae,  slugs,  millipedes,  cut- 
worms, etc. ,  when  exposed  are  killed  as  well  as  plant- 
lice.  Red  spiders,  however,  are  not  entirely  eradicated 
by  the  treatment.  The  foliage  of  single  violets,  like 
California  and  Princess  of  Wales,  are  sometimes  slightly 
injured  by  the  stronger  dose  of  gas.  A  weaker  dose, 
one-tenth  of  a  gramme  potassium  cyanide  per  cubic 
foot,  should  be  used  when  they  are  to  be  treated. 

Other  plants. — Other  plants  on  which  the  gas  has 
been  tried  on  a  small  scale  indicate  that  it  may  prob- 
ably have  quite  a  wide  range  of  usefulness.  It  has 
been  used  on  the  following  plants  at  the  rate  of  one- 
tenth  gramme  of  cyanide  per  cubic  foot  of  space  for 
twenty  minutes  without  injury.  Further  experiment, 
however,  is  necessary  before  the  treatment  can  be 
recommended  for  these:  Alocasia  macrorhiza  variegata; 
Anthurium  crystallinum;  Areca  lutescens;  Aralia  filici- 
folia;  Adiantum  cuneatum;  Adiantum  ballii;  Campy - 
lobotrys  refulgens;  Cissus  discolor;  Cretans  (in  variety)/ 
Cichorium  intybus;  Diffenbachia  lenmannii;  Ficus  elas- 
tica  ;  Fuchsias  (in  variety)  /  Jacaranda  mimosczfolia  / 
Marantas  (in  variety)  /  Nymph&a  candidissima,  and 
odorata  rosea;  Pontederia  crassipes;  Pandanus  veitchii; 
Phrynium  variegatum;  Phyllotcenium  lindenii;  Panax 
victories;  Stenanthium  lindenii. 

Roses. — Perle  des  jardins,  Mermet,  and  Bride. 
The  young  growth  on  roses  is  particularly  sensitive, 
and  has  been  more  or  less  injured  in  all  our  experi- 
ments. 

Carnations. — Scott,    Garfield,    Meteor,     and    Me- 


136  FUMIGATION   METHODS 

Gowan  will  stand  one-tenth  of  a  gramme  of  98  per 
cent,  cyanide  per  cubic  foot  of  space  for  fifteen  minutes 
without  material  injury.  This  will  kill  about  90  per 
cent,  of  the  plant-lice,  but  will  not  kill  thrips.  The 
use  of  the  gas  for  carnations  needs  to  be  more  carefully 
investigated  before  it  is  recommended.  The  same  is 
true  of  chrysanthemums,  on  which  it  has  been  tried 
with  only  partial  success,  the  young  growth  being 
very  sensitive. 

Grapes  under  glass. — The  gas  has  been  used  with 
success  in  New  Zealand  for  the  mealy  bug,  DaElylopius 
adonidum  L,,  at  the  rate  of  one-third  of  an  ounce  98 
per  cent,  cyanide  to  100  cubic  feet.  This  is  equivalent 
to  nine-hundred ths  gramme  per  cubic  foot.  The  gas 
is  liberated  after  dark  and  left  in  till  next  morning, 
when  thorough  ventilation  is  given.  It  largely 
escapes,  however,  during  the  night.  The  treatment 
is  said  not  to  injure  the  plants  in  the  least. 

Tomatoes. — Dr.  J.  Fisher,  on  October  29,  1898, 
reports  using  the  gas  for  white  fly  {Aleyrodes  sp. )  on 
tomatoes.  The  gas  from  one  ounce  of  pure  cyanide  of 
potassium  for  each  1,000  cubic  feet,  left  in  the  house 
over  night,  killed  all  the  insects  without  injury  to  the 
plants.  This  method  should  receive  careful  trial  by 
other  experimenters. 

Other  experiments  in  greenhouses. — For  some  years 
in  the  large  greenhouses  connected  with  the  Massa- 
chusetts Agricultural  College  considerable  difficulty 
has  been  experienced  with  mealy  bugs  and  various 
species  of  scale  insects  on  large  vines,  palms,  begonias, 
orange  trees,  acacias,  etc.  After  a  thorough  trial  of 


GREENHOUSE   AND   COLD   FRAME   FUMIGATION    137 

numerous  insecticides,  hydrocyanic  acid  gas  was  used. 
The  work  was  placed  in  the  hands  of  H.  D.  Hemen- 
way.  All  the  results  obtained  were  not  conclusive, 
and  it  is  impossible  to  give  definite  details  relative  to 
future  work.  Some  of  these  results,  however,  are  in- 
teresting, and  are  given  herewith.  Other  tests  should 
be  made. 

After  several  preliminary  experiments  with  some 
of  the  more  delicate  plants  in  a  wooden  box,  two 
rooms,  known  as  the  stove  and  cactus,  were  fumigated 
at  the  same  time,  the  connecting  doors  between  them 
having  been  opened.  Many  of  the  cacti  were  infested 
with  the  common  cactus  scale,  Diaspis  cacti.  In  the 
stove-room,  all  through  the  twining  vines,  were  white 
waxy  threads  protecting  the  eggs  and  young  mealy 
bugs. 

The  cactus-room  contained  7,076  cubic  feet  of  air 
space  and  the  stove-room  7,357  cubic  feet.  Forty 
ounces  of  potassium  cyanide  were  used  in  each  room, 
and  they  were  kept  closed  for  thirty  minutes.  The 
ventilators,  which  had  been  previously  prepared,  were 
then  opened  from  the  outside.  The  temperature  of 
the  house  was  about  60°  F.  The  conditions  of  the 
weather  were  perfect  for  such  a  test,  as  it  was  rain- 
ing, the  water  filling  all  the  cracks  in  the  house,  and 
thus  preventing  the  escape  of  the  gas.  It  was  also 
warm  outside,  so  the  house  was  not  cooled  too  low 
while  the  ventilators  were  open.  It  was  perfectly 
dark.  The  ventilators  were  left  open  for  about  an 
hour,  and  closed  for  the  night. 

The  room  contained  many  different  kinds  of  cacti, 
begonias  in  variety,  passifloras,  allamandas,  bananas 


138  FUMIGATION   METHODS 

in  fruit,  ferns,  palms,  and  a  large  variety  of  general 
stove  plants.  Not  only*were  the  mealy  bugs,  scales, 
and  aphides  destroyed,  but  a  large  per  cent,  of  sow 
bugs  were  found  dead  on  the  walks  and  under  the  moss 
which  covered  the  floor  of  the  solid  bed  in  the  stove- 
room.  Even  the  earthworms  on  the  surface  of  the  soil 
under  the  moss  were  dead. 

Another  house  containing  22,729  cubic  feet  of  space 
was  fumigated,  using  one  ounce  potassium  cyanide  to 
every  285  cubic  feet.  It  contained  carnations,  smilax, 
violets,  coleus,  chrysanthemums,  small  lettuce,  cut- 
tings, and  small  plants  of  bedded  stock.  It  was  in- 
fested with  the  common  mealy  bug,  Dactylopius  de- 
structor, green  fly,  and  the  white-tailed  mealy  bug, 
Orthezia  insignis.  It  was  fumigated  for  thirty  min- 
utes upon  a  cloudy  morning,  yet  in  daylight.  The  in- 
sects were  mostly  killed,  but  some  of  the  plants  were 
badly  injured.  This  was  especially  true  in  case  of  the 
smilax,  the  upper  leaves  of  carnations  and  lettuce. 
Much  of  the  latter,  which  was  very  small  and  in  full 
light,  was  killed,  while  some  that  was  shaded  showed 
much  less  injury.  The  smilax  and  carnations  recov- 
ered in  time,  but  received  a  severe  check.  Smilax  and 
more  delicate  plants  have  been  subjected  to  double 
this  strength  of  gas  by  the  writer,  in  darkness,  without 
injury. 

About  the  middle  of  January  a  camellia-room  was 
fumigated  with  one  ounce  potassium  cyanide  to  every 
3,000  cubic  feet.  The  room  contained  6,196  cubic  feet, 
and  2.06  ounces  cyanide  were  used.  It  was  fumigated 
at  night  about  six  o'clock,  and  remained  closed  until 
morning. 


GREENHOUSE   AND   COLD   FRAME   FUMIGATION    139 

The  insects  present  were  green  fly,  mealy  bug,  and 
Fuller's  leaf  beetle.  The  plants  were  coleus,  azaleas 
in  bloom,  heliotrope,  ferns,  hoya,  jasmins,  polygala, 
hibiscus,  ericas,  orange  trees,  camellias,  cinerarias,  and 
oxalis.  The  temperature  went  below  50°  F.  No 
plants  were  injured.  Part  of  the  green  flies  were 
killed,  but  mealy  bug  and  leaf  beetle  were  not  injured. 

Another  trial  was  made  in  the  camellia-room  just 
mentioned  a  few  days  later  with  gas  generated  from 
one  ounce  cyanide  to  2,000  cubic  feet  of  space.  The 
exposure  was  continued  throughout  the  night.  No 
plants  were  injured.  The  green  flies  were  all  killed, 
but  only  a  few  of  the  mealy  bugs  were  destroyed. 

A  few  days  later  another  test  was  made  in  the  same 
room,  using  one  ounce  cyanide  for  each  1,000  cubic 
feet.  The  temperature  of  the  room  was  slightly  above 
50°  F.  With  the  exception  of  heliotrope  and  coleus, 
the  plants  were  the  same  as  used  in  the  two  previous 
tests.  All  the  mealy  bugs  were  destroyed.  It  would 
seem  from  these  tests  that  the  gas  can  be  used  in  a 
greenhouse,  under  such  conditions,  generated  from  one 
ounce  cyanide  in  1,000  cubic  feet  of  space,  with  good 
results  upon  the  common  mealy  bug. 

Many  other  tests  were  made,  including  the  vege- 
table house.  The  cyanide  was  used  at  the  rate  of  one 
ounce  for  each  3,000  cubic  feet  of  space  enclosed.  The 
temperature  was  about  56°  F.  The  plants  fumigated 
were  lettuce,  radishes,  papyrus,  smilax,  cinerarias,  and 
kale.  The  lettuce  and  cinerarias  were  badly  covered 
with  green  fly.  Nearly  all  green  fly  was  killed,  even 
under  the  lower  leaves  of  the  lettuce  which  had  com- 
menced to  head.  There  was  no  injury  to  plants. 


140 


FUMIGATION   METHODS 


Estimating  cubic  contents. — The  following  excellent 
method  for  determining  the  cubic  contents  of  a  green- 
house has  been  suggested  by  Dr.  B.  T.  Galloway:  In  all 
cases  where  fumigation  with  this  gas  is  to  be  followed 
it  is  necessary  to  first  determine  accurately  the  cubic 
contents  of  each  house.  The  determination  of  the 


FIG.    72 — DIAGRAM    ILLUSTRATING     METHOD    OF    DETERMINING 
CUBIC   CONTENTS    OF    GREENHOUSE.       (AFTER    GALLOWAY) 

cubic  contents  of  the  house,  while  in  itself  a  compara- 
tively simple  problem,  has,  in  the  eyes  of  many  grow- 
ers, difficulties  which  they  are  not  willing  to  under- 
take. The  cubic  contents  can  be  determined  by  a 
comparatively  simple  mathematical  calculation,  but 
perhaps  the  easiest  way  is  by  the  square  method. 
This  involves  nothing  more  difficult  than  the  mere 
counting  of  a  number  of  squares.  On  examining 
Fig.  72  the  simplicity  of  the  method  will  become 


GREENHOUSE   AND   COLD   FRAME   FUMIGATION    141 

apparent.  Procure  from  a  stationery  store  or  art  sup- 
ply store  some  cross-section  paper,  such  as  represented 
in  the  figure.  In  this  particular  case  squares  of  three 
sizes  are  shown,  the  largest  being  one-half  inch,  the 
next  one-fourth  inch,  and  the  smallest  one-sixteenth 
inch  square.  The  one- fourth  inch  squares  may  repre- 
sent feet.  Now  determine  the  dimensions  of  the 
house,  that  is,  the  length,  width,  hight  to  ridge,  and 
hight  on  sides,  and  make  a  sketch  as  shown,  each 
square  or  one-fourth  inch  representing  i  square  foot. 
This  particular  house,  it  will  be  seen,  is  18  feet  (18 
squares)  wide,  12  feet  to  the  ridge,  6^/2,  feet  high  at 
the  back,  and  4^  feet  high  in  front. 

The  ridge  stands  5  feet  from  the  back  wall,  as 
shown  in  the  sketch.  After  the  lines  are  drawn,  sim- 
ply count  the  squares  inclosed,  and  the  number  of 
squares  will  be  the  number  of  square  feet.  The  parts 
of  squares,  that  is,  where  a  line  divides  a  square,  can 
be  easily  determined  by  counting  the  smallest  squares, 
or  by  the  eye,  and  by  adding  these  fractions  of  squares 
together  the  number  of  whole  squares  may  be  readily 
found.  After  the  number  of  square  feet  is  obtained  it 
is  only  necessary  to  multiply  this  by  the  length  of  the 
house  in  feet  and  the  result  will  be  the  cubic  contents. 
For  example,  supposing  the  house  in  question  is  100 
feet  long,  it  contains  150^  squares  or  square  feet,  and 
150^  multiplied  by  100  equals  15,050  cubic  feet.  The 
whole  operation  requires  less  time  than  it  takes  to 
describe  it,  and  will  apply,  of  course,  to  a  house  of  any 
shape  or  size.  It  may  be  added  that  if  the  cross- 
section  paper  can  not  be  obtained  readily  the  sections 
or  squares  can  be  laid  off  with  a  rule  and  lead  pencil 


1 42 


FUMIGATION   METHODS 


and  practically  the  same  results  obtained.  In  any 
event,  it  is  only  necessary  to  get  an  accurate  outline 
drawing  of  the  section  of  the  house,  and  by  projecting 
this  over  squares  as  indicated  the  number  of  square  feet 
in  the  section  can  be  readily  determined. 

The  cubic  contents  of  the  two  styles  of  greenhouses 
shown  in  Fig.  73  are  easily  estimated,  according  to  the 
following  scheme  by  Professors  Woods  and  Dorsett. 
At  the  left  is  an  even  span  house  100  feet  long,  12  feet 
wide,  2  feet  on  the  sides,  and  5  feet  6  inches  from  the 


FIG.    73 — EVEN    AND    THREE-QUARTER    SPACE    HOUSES    AT    LEFT 
AND    RIGHT — END    SECTIONS.       (AFTER    WOODS    AND    DORSETT) 

the  surface  of  the  beds  to  the  ridge,  with  a  walk  14 
inches  wide  and  15  inches  deep.  To  determine  accu- 
rately the  number  of  cubic  feet  in  a  house  make  a 
rough  drawing  showing  a  cross-section,  and  divide  the 
space  into  triangles  and  rectangles  by  drawing  a  line 
connecting  the  two  wall  plates  and  one  from  the  ridge 
at  right  angles  to  this  ;  mark  on  each  its  respective 
length  in  feet  and  inches.  Compute  the  number  of 
cubic  feet  in  each  of  the  rectangles  and  triangles.  In 
the  even  span  house,  shown  at  the  left,  the  number  of 
cubic  feet  of  space  in  the  walk  is  found  by  multiplying 
the  width  by  the  depth  by  the  length,  thus:  Multiply 


GREENHOUSE  AND   COLD   FRAME   FUMIGATION    143 

I  foot  2  inches  by  i  foot  3  inches  by  100  feet ;  redu- 
cing to  inches,  we  have  14  inches  multipled  by  15  inches 
by  1,200  inches  equals  252,000  cubic  inches  ;  dividing 
this  result  by  1,728,  the  number  of  cubic  inches  con- 
tained in  a  cubic  foot,  we  have  145.83  cubic  feet.  The 
rectangle  A  D  G  F\$>  computed  in  the  same  way,  ex- 
cept that  in  this  case  it  is  not  necessary  to  reduce  the 
feet  to  inches.  It  would  be  12  feet  multiplied  by  2 
feet  by  100  feet  equals  2,400  cubic  feet. 

The  rule  generally  given  for  calculating  the  area  of 
a  right-angle  triangle  is  to  multiply  the  base  by  the 
perpendicular  and  divide  the  product  by  2.  The  result 
multiplied  by  the  length  of  the  house  will  give  the 
number  of  cubic  feet  the  triangular  portion  contains. 
For  example,  taking  the  triangle  A  C  E  :  6  feet  mul- 
tiplied by  3.5  feet  equals  21  feet,  divided  by  2  equals 
10.5  feet,  multiplied  by  loo  feet  equals  1,050  cubic 
feet.  The  area  of  the  triangle  BCD  and  the  cubic 
feet  in  this  part  of  the  house  are  determined  in  the 
same  way  ;  or,  in  this  case,  since  the  triangles  are 
equal,  the  desired  result  is  obtained  by  multiplying  the 
number  of  cubic  feet  in  the  triangle  ACE  by  2  ; 
1,050  multiplied  by  2  equals  2,100  cubic  feet.  The 
contents  of  this  house  is  therefore  145.83  plus  2,400 
plus  2,100  equals  4,645.83  cubic  feet;  this  result 
multiplied  by  the  required  dose  per  cubic  foot  of  space 
will  give  the  amount  of  cyanide  of  potassium  necessary 
for  one  fumigation, 

At  the  right,  in  Fig.  73,  is  a  cross-section  of  a  three- 
quarter  span  house  100  feet  long,  18  feet  wide,  front 
wall  4  feet  4  inches,  back  wall  6  feet  4  inches,  and  i 
feet  10  inches  to  the  ridge.  The  cubic  contents  of  this 


144  FUMIGATION   METHODS 

house  is  determined  in  the  same  manner,  except  that 
the  two  triangles  being  unequal,  each  one  will  have  to 
be  calculated  separately.  The  house  contains  15,050 
cubic  feet.  It  will  thus  be  seen  that  the  cubic  con- 
tents of  a  house  or  frame  of  any  style  can  be  readily 
determined  by  simply  dividing  a  cross-section  of  the 
same  into  the  necessary  number  of  triangles  and  reel- 
angles,  and  calculating  as  demonstrated  above. 

Cold  frames. — That  cold  frames  can  be  successfully 
fumigated  has  been  shown  by  recent  practical  work. 
Make  the  frames  as  nearly  air-tight  as  possible,  and 
cover  them  with  blankets  or  canvas  if  necessary. 
Kstimate  the  cubic  contents  of  air  space  inclosed,  and 
then  calculate  the  amount  of  cyanide  necessary.  For 
example,  suppose  a  frame  contained  567  cubic  feet. 
Multiply  this  by  0.15,  an  equivalent  of  0.15  gramme 
cyanide  per  cubic  foot.  Therefore,  567  x  0.15,  equals 
85.05  grammes;  reduced  to  ounces  by  dividing  by 
28.35,  as  there  are  28.35  grammes  in  an  ounce,  gives 
(85.05  divided  by  28.35)  3  ounces  the  amount  of  cya- 
nide required. 

This  inclosure  would  require  3  ounces  cyanide,  4^ 
ounces  sulphuric  acid  and  6^  ounces  of  water.  After 
the  cyanide  is  determined  it  is  easy  to  estimate  the 
acid  and  water.  Use  a  half  more  acid,  liquid  measure, 
than  cyanide,  and  a  half  more  water  than  acid.  Weigh 
the  cyanide  and  wrap  it  in  paper  or  a  bag.  Measure 
the  acid  in  a  glass  beaker,  marked  ounces  on  the  side, 
and  pour  it  in  an  earthern  jar  or  china  bowl ;  measure 
the  water  and  pour  upon  the  acid.  When  everything 
is  in  readiness  drop  the  cyanide,  paper  and  all,  into 
the  liquids  and  close  the  frames  quickly. 


GREENHOUSE  AND   COLD   FRAME   FUMIGATION    145 

Leave  exposed  twenty  to  thirty  minutes,  and  no 
longer.  Do  the  work  on  a  dark,  cloudy  day,  or  late 
in  the  evening,  or  at  night.  Thoroughly  air  the 
frames  afterward,  and  empty  the  residue  in  the  jars. 
Do  not  inhale  the  gas,  and  do  not  handle  the  cyanide 
carelessly.  Both  are  deadly  poison  if  breathed  or 
swallowed. 

General  summary. — (i)  The  cubic  contents  of  the 
house  and  the  amount  of  cyanide  to  be  used  should  be 
carefully  determined.  (2)  The  enclosure  should  be 
made  as  nearly  gas-tight  as  possible.  (3)  The  venti- 
lators should  be  arranged  so  as  to  be  opened  from  the 
outside.  (4)  Place  the  screw-eyes  in  their  proper 
.places  and  run  the  string  through  them.  (5)  Deter- 
mine whether  the  bag  of  cyanide  is  directly  over  the 
jar  before  the  chemicals  are  placed  in  it.  (6)  Measure 
the  acid  and  water  carefully,  place  it  in  the  vessels, 
hang  the  bag  of  cyanide  directly  over  them,  and  arrange 
the  protection  sheets  of  paper.  (7)  The  bags  should 
be  lowered  by  loosening  the  string  from  the  outside 
door.  (8)  Doors  should  be  properly  closed  and  left 
locked  the  desired  length  of  time.  (9)  After  proper 
exposure  open  the  ventilators  and  doors  from  the  out- 
side, and  leave  them  thirty  or  forty  minutes  before 
entering  the  house.  After  that  time  they  can  be  closed 
and  left  until  morning.  (10)  The  contents  of  the  jars 
should  be  buried  or  thrown  upon  a  manure  pile.  ( 1 1 ) 
Jars  should  be  thoroughly  washed  with  cold  water  and 
set  away  for  future  use. 

A  practical  application . — In  reply  to  a  recent  letter, 
Edward  A.  Moseley,  of  Washington,  D.  C.,  says:  "I 
most  certainly  believe  cyanide  fumigation  is  practical. 


146  FUMIGATION   METHODS 

Last  year  in  my  largest  Jiouse  I  only  found  it  necessary 
to  fumigate  once,  and  until  the  violets  were  thrown  out 
this  spring  I  never  saw  another  aphis  in  it.  I  cannot 
now  give  you  exact  information  in  regard  to  the  cost 
of  fumigation. 

"  I  do  not  entrust  the  operation  to  any  one,  as  the 
risk,  which  I  believe  to  be  great,  I  take  myself. 
Therefore  all  the  fumigation  which  I  have  done  I  have 
done  alone,  except  with  a  friend  to  assist;  but  the 
people  who  work  about  the  house  have  nothing  to  do 
with  it.  Fumigating  is  done  about  an  hour  or  two 
after  dark.  I  grow  Farquhar,  Lady  Campbell,  and 
Imperial  violets;  also  a  few  La  France.  Last  year  I 
had  some  of  them  in  one  house.  The  leaves  of  the 
La  France  were  slightly  injured  by  an  exposure  of 
twenty-one  minutes. 

"The  black  aphis  were  very  prevalent;  in  fact, 
the  plants  were  completely  covered  with  them  when  I 
gave  the  application  of  which  I  have  spoken,  but  it 
cleaned  them  out.  I  have  used  it  also  in  violet  frames 
and  in  a  mushroom  house.  In  the  latter  case  I  used 
it  with  great  strength.  I  found  mice,  snails,  roly- 
polys,  and  earthworms  dead  in  the  morning.  This  I 
put  in  and  allowed  to  stay  all  night.  I  have  also 
found  from  experiments  that  nothing  can  breathe  the 
gas  and  live. 

' '  In  my  opinion  no  one  can  successfully  grow 
violets,  at  least  in  this  vicinity,  who  does  not  use  the 
gas.  I  have  now  one  house  23^  feet  wide  by  200  feet 
long,  one  20  feet  wide  by  100  feet  long,  one  12  feet 
wide  by  60  feet  long,  all  devoted  to  the  growing  of 
violets. ' ' 


CHAPTER  XV 
SMALL   FRUITS  AND  PLANTS 

SIOMK  method  of  destroying  plant-lice,  leaf- folders, 
I  and  other  insects  on  small  plants  has  long 
been  sought  by  economic  workers.  These 
pests  can  not  be  reached  with  sprays,  and  the 
application  of  certain  gases  seemed  practical.  In  the 
spring  of  1898  the  writer  began  a  series  of  experiments 
with  hydrocyanic  acid  gas  on  strawberry  plants  to 
determine  the  strength  that  could  be  used  with  safety 
for  the  destruction  of  the  root-louse,  Aphis  for besi. 
In  these  tests  it  was  shown  that  strawberry  plants,  dug 
in  the  spring,  could  be  fumigated  successfully  before 
being  transplanted.  It  was  found  also  that  the  plants 
could  be  dipped  in  soap  and  tobacco  solutions  with 
fair  results,  but  the  process  was  slow,  expensive,  arid 
difficult.  The  gas  remedy  was  cheaper,  more  certain, 
and  easier  to  apply. 

Amount  of  gas  for  strawberry  plants. — With  the 
ordinary  run  of  strawberry  plants  as  they  are  taken 
from  the  nursery,  two-tenths  (0.2)  gramme  cyanide 
per  cubic  foot,  exposed  fifteen  to  twenty  minutes,  will 
be  effective  in  killing  the  lice  without  injury  to  the 
plants.  The  roots  should  be  as  free  as  possible  from 
dirt,  and  the  plants  should  be  reasonably  dry.  There 
is  always  more  or  less  moisture  on  young  plants,  but 
under  no  circumstances  should  they  be  drenching  wet 
at  time  of  fumigation.  Plants  should  not  be  closely 

i47 


148  FUMIGATION   METHODS 

packed,  but  laid  loosely  upon  trays  in  the  fumigating 
box  or  room.  The  details  of  making  and  handling 
the  gas  are  the  same  as  that  for  nursery  stock  and 
greenhouse  work.  The  apparatus  to  be  used  will 
depend  upon  the  number  of  plants  grown  and  handled 
annually.  A  convenient  box  for  fumigating  straw- 
berry plants  is  shown  in  Fig.  71. 

Experimental  and  practical  tests. — At  the  Dela- 
ware Experiment  Station  a  very  complete  series  of 
tests  were  started  by  Prof.  G.  Harold  Powell  and 
completed  by  Prof.  K.  Dwight  Sanderson.  Several 
infested  plants  were  fumigated  and  placed  in  paper 
bags,  where  they  were  left  and  examined  twelve  hours 
later.  The  following  amounts  of  cyanide  were  found 
sufficient  for  the  destruction  of  the  root-louse:  One- 
tenth  gramme  (o.  i)  per  cubic  foot  space,  exposed 
twenty  minutes;  fifteen-hundredths  (0.15)  gramme  for 
fifteen  minutes;  two- tenths  (0.2)  gramme  for  ten  min- 
utes; three-tenths  (0.3)  gramme  for  five  minutes.  In 
the  same  series  where  0.3  gramme  cyanide  was  used, 
all  the  lice  were  killed  where  the  exposure  was  only 
five  minutes.  It  is  not  desirable  to  use  these  larger 
amounts  even  for  a  short  exposure.  The  work  by 
Professors  Powell  and  Sanderson  corroborates  the  vari- 
ous tests  of  the  writer  that  the  two- tenths  gramme 
formula  is  satisfactory  when  properly  handled.  Under 
some  circumstances  a  few  lice  may  be  secreted  among 
the  crown  leaves  and  possibly  escape  where  large  num- 
bers of  plants  are  fumigated.  This  danger  can  be 
overcome  largely  by  loose  packing  before  fumigation. 

Practical  tests. — Karly  in  April  Professor  Sanderson 


FRUITS   AND   PLANTS  149 

fumigated  12,000  Bubach,  Excelsior,  and  Johnson's 
Early  strawberry  plants.  These  had  been  packed  in 
moss  while  en  route  from  the  nursery  for  nearly  a 
week,  but  were  in  good  condition.  About  4,000 
Tennessee  Prolific  just  dug  were  also  fumigated.  The 
roots  were  cut  back  and  fumigated  in  lots  of  1,500  to 
2,000  for  ten  minutes  with  two-tenths  (0.2)  grammes 
cyanide  per  cubic  foot.  The  plants  were  set  at  once 
after  fumigation  and  were  not  watered.  They  made  a 
good  stand,  very  few  dying — so  few  that  there  was  no 
question  that  the  gas  had  done  no  injury,  as  two  check 
rows  were  left  which  made  no  better  stand.  April  2oth 
over  10,000  Bubach  plants  were  fumigated.  These 
had  been  dug  for  one  or  two  days  and  packed  in  a 
barrel.  They  were  quite  wet  when  fumigated.  About 
8,000  were  fumigated  with  one-tenth  (o.  i)  gramme 
cyanide  per  cubic  foot  for  ten  minutes,  and  i  ,500  at  same 
dose  for  fifteen  minutes,  while  nearly  i  ,000  were  planted 
unfumigated  as  a  check.  After  these  plants  were  fumi- 
gated they  were  aired  five  minutes,  roots  dipped  in 
water,  and  repacked  in  barrels.  They  were  set.  out 
three  days  later.  The  plants  showed  no  injury  from 
the  gas,  all  making  an  equally  good  stand. 

In  the  experiments  of  Professor  Sanderson  the 
earth  was  firmly  packed  around  the  open  bottom  of  the 
box  used.  The  plants  were  well  cleaned  of  earth,  laid 
on  trays,  the  bundles  being  cut  open  and  thoroughly 
loosened.  The  lid  of  the  box  was  then  closed  and 
fastened.  A  coffee  cup  or  similar  vessel  was  placed  in 
the  lower  corner  of  the  box  by  the  door,  and  into  it  was 
first  dropped  a  vial  containing  a  proper  amount  of  the 
cyanide  in  solution.  A  vial  containing  the  sulphuric 


150  FUMIGATION   METHODS 

acid  was  then  dropped  in  and  the  door  quickly  closed. 
The  vials  were  dropped  in  with  the  mouths  down,  and 
the  contents  drained  out  gradually,  avoiding  a  puff  of 
the  gas  by  too  rapid  generation.  The  box  was  kept 
closed  for  ten  minutes,  or  as  long  as  desired.  Both 
doors  were  then  thrown  open  and  the  trays  lifted  out, 
so  that  the  plants  were  thoroughly  aired. 

The  cyanide  solution  should  be  secured  from  a 
druggist,  put  up  in  homeopathic  vials,  one  dose  in  each 
vial.  The  solution  consists  of*  100  grammes  98  per  cent, 
potassium  cyanide  dissolved  in  water  to  make  200 
cubic  centimeters  solution.  The  amount  necessary  for1 
each  dose  is  easily  computed:  multiplying  the  cubic 
contents  of  the  box  by  0.4  will  give  the  number  of 
cubic  centimeters  of  the  solution  to  be  used,  this  giving 
a  strength  of  o.  2  gramme  potassium  cyanide  per  cubic 
foot.  Use  an  equal  amount  of  sulphuric  acid,  which 
can  be  readily  measured  into  empty  vials.  Thus  for  a 
box  2  x  2  x  2^£  feet,  or  10  cubic  feet,  4  cubic  centi- 
meters of  the  solution,  or  a  two- drachm  vial  half  full, 
and  an  equal  amount  of  sulphuric  acid  (best  grade 
commercial,  1.85  specific  gravity)  would  be  used  for 
a  strength  of  0.2  gramme  potassium  cyanide  per  cubic 
foot,  or  the  same  vial  three-quarters  full  for  a  strength 
of  0.3  gramme  potassium  cyanide  per  cubic  foot. 

Small  plants  in  the  field. — For  individual  plants, 
such  as  melon,  cucumber,  cabbage,  etc. ,  a  small  cover 
is  needed.  In  many  cases  where  only  a  few  plants  are 
to  be  treated,  a  two-gallon  wooden  pail  or  other  simi- 
lar vessel  will  do.  Paper  or  canvas  covered  boxes,  one 
or  two  feet  square  at  the  base,  and  fifteen  to  twenty 
inches  high,  can  be  made  cheaply  and  used  to  good 


FRUITS   AND   PLANTS  151 

advantage.  In  his  experiments  Professor  Sanderson 
used  small  paper  covers,  pyramidal  in  shape,  the  apex 
being  eight  inches  high  and  fastened  to  the  inside  of  a 
wooden  frame  three  inches  high  by  twenty  inches 
square.  The  lower  edge  of  the  frame  was  beveled  on 
the  lower  edge  and  could  be  easily  pressed  into  the 
soil.  A  good  quality  of  building  paper,  cut  in  one 
piece,  can  be  used  as  covers.  The  cost  of  the  covers 
complete  should  not  exceed  four  cents  each. 

After  making  over  seventy-five  tests  Professor 
Sanderson  is  of  the  opinion  that  about  four- tenth  (0.4) 
gramme  cyanide  per  cubic  foot  exposed  ten  minutes 
is  sufficient.  In  some  tests  young  cantaloupes,  fumi- 
gated immediately  after  a  shower,  were  somewhat 
injured.  The  plants  should  be  as  dry  as  possible  and 
the  amount  of  cyanide  reduced  to  three-tenths  (0.3) 
gramme  per  cubic  foot  in  some  cases.  The  seemingly 
large  amount  of  gas  used  on  these  low-growing  plants 
is  due  to  the  fact  that  a  larger  proportion  is  lost  in  the 
small  covers  than  in  a  large  enclosure.  Where  plants 
are  5x5  feet  apart,  the  cost  of  fumigation  per  acre, 
even  at  the  maximum  amount,  is  about  seventy-five 
cents  for  chemicals.  Two  men  with  one  hundred 
covers  should  fumigate  from  three  to  five  acres  per 
day,  depending  somewhat  on  conditions. 

Plants  in  rows. — The  fumigation  of  plants  in  rows 
is  rather  difficult  and  expensive.  To  compensate  for 
the  influence  of  soil  and  foliage,  a  larger  amount  of 
gas  per  cubic  foot  of  space  must  be  used  to  accomplish 
the  same  results  than  in  a  box  or  other  enclosure. 
Prof.  C.  L.  Penny,  chemist  at  the  Delaware  Experi- 
ment Station,  has  shown  conclusively  by  analyses  that 


152  FUMIGATION   METHODS 

when  the  gas  is  used  in  an  elongated  space  the  amount 
of  cyanide  per  cubic  foot  is  no  guarantee,  on  the  one 
hand,  of  sufficient  acid  vapor  to  do  the  work,  nor,  on 
the  other,  of  too  little  to  injure  the  plants.  These 
tests  show  also  that  a  large  amount  of  gas  may  be  ab- 
sorbed by  the  film  of  water  on  damp  foliage,  or  by  the 
soil  in  a  frame  with  the  bottom  open. 

In  field  tests,  therefore,  a  larger  amount  of  gas  than 
that  used  in  the  laboratory  in  a  closed  box  was  re- 
quired to  compensate  the  influence  of  soil  and  foliage. 
In  a  ten-foot  frame,  triangular  in  cross-section,  with  a 
cubic  capacity  of  8^  feet,  or  a  ratio  of  2^  soil  surface 
to  one  of  volume,  Professor  Sanderson  found  just 
twice  as  much  gas  was  required  to  be  generated 
from  two  points  to  be  effective  as  that  in  a  wooden  box 
containing  10  cubic  feet  capacity  and  5  square  feet 
soil  surface,  having  an  almost  opposite  ratio  of  two 
of  volume  to  one  of  soil  surface.  The  materials  and 
cost  of  constructing  frames  for  the  fumigation  of  plants 
in  rows  is  slight.  Frames,  triangular  cross-section  10 
feet  long  by  10  inches  high  and  24  inches  wide  at  the 
bottom,  have  been  found  very  satisfactory  by  Professor 
Sanderson.  With  twelve  such  fumigators  an  acre  of 
plants,  where  the  rows  are  three  feet  apart,  can  be  gone 
over  in  about  two  days.  The  cost  of  chemicals,  not 
including  labor,  would  be  about  three  dollars  per  acre. 


CHAPTER  XVI 

APPLICATION   IN    MILLS,   ELEVATORS,   AND 
OTHER    ENCLOSURES 

M^^ANY  gases  and  other  materials  have  been  used 
in  mills  and  other  enclosures  for  the  de- 
struction of  insect  pests.  Gas  generated  from 
sulphur  is  not  only  dangerous  to  inhale,  but 
is  liable  to  injure  manufactured  products.  The  writer 
reported  several  years  ago  the  serious  results  upon 
manufactured  products  in  a  mill  where  sulphur  fumes  , 
were  used.  Smoke  or  fumes  generated  from  tobacco 
are  not  desirable  on  account  of  the  disagreeable  odor 
and  the  after-effects  upon  grain  and  the  manufactured 
products.  Both  of  these  materials  being  generated 
with  fire,  the  danger  attending  application  in  mills 
and  other  places  is  increased,  and  their  use  is  seriously 
objected  to  by  insurance  companies. 

On  the  other  hand,  carbon  bisulphide  has  many 
advantages  over  sulphur  and  tobacco  ;  it  can  be  used 
without  danger  of  injuring  either  the  grain  or  manu- 
factured products,  and  is  generated  without  the  use  of 
fire.  Yet  many  insurance  companies  will  not  permit 
their  patrons  to  use  it,  except  at  their  own  risk,  on 
account  of  its  explosive  nature  when  the  fumes  are 
mechanically  mixed  with  air.  It  is,  perhaps,  the  safest 
and  most  reliable  remedy  suggested  for  use  in  build- 
ings and  other  enclosures  where  large  quantities  of 
grain  and  other  materials  are  stored,  due  largely  to 
the  fact  that  its  fumes  are  heavier  than  air. 

Sometimes  it  is  desirable  to  use  carbon  bisulphide 

153 


154  FUMIGATION    METHODS 

in  connection  with  hycjrocyanic  acid  gas  in  buildings 
and  other  enclosures.  On  one  occasion  the  writer  had 
a  large  quantity  of  grain  badly  infested  with  insects 
stored  in  an  old  building.  The  wheat  was  confined 
in  several  large  rooms  more  or  less  open.  Carbon 
bisulphide  was  used  liberally  for  the  destruction  of  the 
insects  in  the  grain,  but  it  was  found  that  a  large 
number  of  the  creatures  in  the  upper  part  of  the  build- 
ing escaped,  owing  to  the  openness  of  the  enclosure. 
The  building  was  made  as  tight  as  possible  by  hang- 
ing blankets,  fertilizer  bags,  etc. ,  over  the  cracks,  and 
a  charge  of  hydrocyanic  acid  gas  was  liberated. 
Double  the  quantity  ordinarily  recommended  for  a 
tight  enclosure  was  used.  The  experiment  was  largely 
successful,  and  the  insects  were  thoroughly  destroyed 
both  in  the  grain  and  throughout  the  building.  It  is 
not  desirable,  however,  to  generate  the  twro  gases  at 
the  same  time.  In  this  instance  the  hydrocyanic  acid 
gas  was  applied  forty-eight  hours  after  the  carbon 
bisulphide  was  used. 

The  strongest  arguments  in  favor  of  hydrocyanic 
acid  gas  are:  (i)  it  is  generated  without  fire;  (2)  it  is 
comparatively  cheap;  (3)  non-inflammable  and  non- 
explosive  when  generated  with  normal  amounts;  (4) 
does  not  injure  grain  or  manufactured  products, 
machinery,  furniture,  or  equipment  of  any  kind;  (5) 
leaves  no  odor  or  residue  after  fumigation;  (6)  is 
lighter  than  air,  and  quickly  permeates  all  cracks  and 
crevices  in  which  pests  hide;  (7)  can  be  used  at  night 
or  in  the  daytime  at  pleasure;  (8)  creates  a  death 
atmosphere  in  which  no  animal  can  live,  including  rats, 
mice,  and  other  vermin;  (9)  its  very  deadly  nature 


MIU,S   AND   OTHER   BUILDINGS  155 

when  inhaled  lessens  the  possibility  of  accident,  and 
(10)  it  affords  insurance  companies  and  others  all  the 
protection  possible  under  such  conditions. 

First  use  of  hydrocyanic  acid  gas  in  mills,  etc. — The 
use  of  hydrocyanic  acid  gas  for  the  distraction 
of  insects  in  mills,  elevators  and  other  large  enclosures 
where  grain  is  stored  and  manufactured  was  first 
suggested  by  the  writer  in  an  article  in  the  American 
Miller  for  March,  1898.  Up  to  that  time,  we  believe, 
no  attempt  had  been  made  to  fumigate  large  buildings 
with  this  gas  for  the  destruction  of  vermin.  In  this 
article  attention  was  called  to  a  large  mill  in  North 
Carolina,  overrun  with  cockroaches,  and  the  following 
statement  was  made  :  ' '  We  are  going  to  try  a  new 
remedy.  It  has  never  been  used,  to  my  knowledge,  for 
destroying  insects  in  mills.  It  is  simple  and  easy  to 
apply,  but  a  very  dangerous  and  deadly  poison,  and 
must,  like  dynamite,  gunpowder,  kerosene,  or  carbon 
bisulphide,  be  handled  cautiously  and  by  expert 
hands.  Our  new  remedy  is  hydrocyanic  acid  gas,  one 
of  the  most  deadly  poisons  known.  I  have  used  this 
gas  in  my  experimental  work  the  past  two  years 
for  killing  insects  upon  young  fruit  trees,  nursery 
stock  and  in  bearing  orchards,  and  in  buildings  for 
destroying  rats,  with  marked  success.  I  will  now 
apply  it  to  the  modern  mill  and  storehouse,  and  my 
candid  belief  is  that  it  will  be  one  of  the  coming 
remedies  for  all  vermin,  including  rats  and  mice, within 
such  enclosures. ' ' 

The  opportunity  did  not  offer  itself  at  the  time  for 
the  experiment  and  we  were  obliged  to  let  the  matter 
drop.  The  spring  of  1899,  however,  offered  us  a 


156  FUMIGATION  METHODS 

chance  to  use  the  gas  in  a  granary  and  storehouse. 
The  results  were  so  gratifying  we  decided  to  apply  the 
same  methods  to  a  modern  mill,  if  an  infested  one 
could  be  found  and  the  owner  would  consent  to  the 
experiment.  Two  infested  mills  where  we  could  try 
the  gas  on  a  large  scale  were  soon  found.  Both 
contained  three  stories  with  basement  and  attic.  One 
was  70  by  40  feet  and  the  other  50  by  50  feet.  Before 
filling  an  entire  building  with  the  gas,  we  decided  to 
confine  our  experiment  to  one  floor.  All  arrange- 
ments were  made  with  a  Pennsylvania  miller  and  final 
directions  were  sent  for  the  work.  The  first  charge 
was  set  off  June  10,  1899,  using  five  pounds  of 
potassium  cyanide,  an  equivalent  of  o.  10  gramme 
cyanide  per  cubic  foot  of  space  enclosed. 

Five  days  later  the  following  letter  was  received 
from  the  owner:  "  We  made  use  of  the  chemicals  sent 
us,  as  directed,  on  the  loth  instant,  and  had  some 
success,  at  least  enough  to  convince  us  that  through 
its  use  we  can  retain  possession  of  our  mill.  Most  of 
the  weevil  on  the  first  floor  are  either  on  the  floor  or 
very  close  to  it,  and  we  find  that  a  good  many  of  them 
escaped  punishment.  In  the  rooms  above  the  first 
floor  we  will  have  a  better  chance  at  them,  they  being 
higher  up  in  places  where  we  can  not  get  at  them 
with  anything  but  gas.  We  would  like  to  have  you 
arrange  to  send  us  enough  of  the  potassium  cyanide  to 
go  through  our  mill  from  the  first  floor  up.  Any 
information  you  can  give  us  concerning  the  second 
treatment  will  be  greatly  appreciated.  We  found  a 
dead  cat  on  the  mill  floor  when  we  went  in  after  airing 
the  room  thoroughly. ' ' 


MILLS   AND   OTHER   BUILDINGS  157 

This  experiment  was  thoroughly  satisfactory,  and 
being  the  first  of  the  kind  ever  tried  in  a  mill,  so  far 
as  known,  was  of  special  importance.  Where  only  a 
single  floor  is  fumigated,  we  would  naturally  expect 
some  insects  in  the  floor  and  beneath  it  to  escape,  as 
the  gas  is  lighter  than  air  and  rises.  A  room,  there- 
fore, would  have  to  be  perfectly  tight,  and  enough 
gas  generated  to  fill  it  before  the  fumes  would  reach 
the  floor  and  penetrate  the  cracks  and  crevices.  It 
would  be  only  a  few  moments  after  fumigation  before 
insects  would  again  come  through  the  cracks  in  the 
floor  from  the  basement  below  and  perhaps  the  floor 
above. 

To  be  successful  in  the  greatest  degree  the  mill 
should  be  thoroughly  filled  at  one  time  with  the  gas. 
For  instance,  if  only  a  single  room  or  floor  is  used  and 
the  gas  is  generated,  the  insects  become  very  uneasy 
when  they  begin  to  feel  uncomfortable,  and  run  here 
and  there  in  search  of  a  crack  through  which  to 
escape;  but  if  every  room  is  full  of  gas  there  is  no 
possible  means  of  escape,  except  through  some  crack 
leading  outdoors. 

Second  experiment  in  mills. — In  an  Ohio  mill, 
June  20,  1899,  we  tried  another  experiment  on  one 
floor  only,  using  ten  pounds  of  cyanide  at  the  rate  of 
0.12  gramme  per  cubic  foot  of  air  space.  The 
chemicals  were  placed,  according  to  my  directions,  in 
the  hands  of  an  expert  chemist.  June  3oth  the  owner 
sent  a  sample  of  web  and  material  from  the  room,  and 
wrote  me  as  follows:  "I  send  you  by  mail,  under 
separate  cover,  a  sample  of  moth,  weevil,  and  bugs  the 
gas  destroyed.  I  wish  to  thank  you  for  what  you 


158  FUMIGATION   METHODS 

have  done  for  me  and  to  tell  you  that  the  experiment 
was  a  grand  success." 

A  careful  examination  of  the  material  sent  showed 
seven  species  of  dead  insects,  as  follows:  (i)  Flour 
moth,  Ephestia  kuehniella,  adults  and  larvae;  (2) 
bolting-cloth  beetle,  Tenebroides  mauritanicus,  adults; 

(3)  American   meal  worm,    Tenebrio  molitor,  adults; 

(4)  flour    weevil,     Tribolium    confusum,    adult    and 
larvae;    (5)    black    carpet    beetle,    Attagenus  piceus, 
adult;  (6)  a  lady  beetle,  and  (7)  a  hemipterous  insect. 
The  latter  two  were,  no  doubt,  feeding  upon  some  soft- 
bodied  creatures,   as  they  are  both  predaceous.     This 
web,  flour,  dust,  and  insects  was  placed  in  a  breeding- 
cage  and  was  under  daily  observation  for  three  weeks 
and  no  life  made  its  appearance.     When  the  package 
was  received  one  living  specimen  of  the  flour  weevil, 
Tribolium  confusum,  was  found.     It  was,  no  doubt,  a 
straggler  from  some  crack  where  the  death  atmosphere 
did  not  reach. 

From  recent  results  we  are  convinced  that  this  gas 
is  one  of  the  most  powerful  and  penetrating  materials 
ever  used  in  a  mill  or  other  buildings  for  the 
destruction  of  vermin.  It  diffuses  so  readily  that  it 
will  permeate  all  parts  of  a  mill  or  enclosure  in  a  few 
minutes.  It  is  a  deadly  poison  if  inhaled  by  a  human 
being,  it  is  true,  but  there  is  no  necessity  of  one 
breathing  the  fumes  if  the  proper  precautions  are 
taken.  The  writer  is  satisfied  that  by  its  use  many 
a  miller  can  retain  possession  of  his  mill  who  would 
otherwise  be  obliged  to  give  it  up  and  acknowledge,  in 
the  "struggle  for  existence,"  it  is  the  ''  survival  of 
the  fittest ' '  that  wins  out.  It  is  humiliating,  indeed, 


MILLS  AND   OTHER   BUILDINGS  159 

to  be  forced  to  concede  that  the  flour  moth  or  weevil 
is  the  fittest  thing  in  existence,  but  some  millers  have 
actually  been  forced  to  abandon  their  mills  on  account 
of  these  insect  foes. 

Necessary  preparations. — In  fumigating  a  mill,  ele- 
vator, warehouse  or  other  enclosure  containing  stored 
grain  or  manufactured  products,  several  things  are  to 
be  taken  into  consideration. 

1 .  The  nature  of  the  structure  has  a  great  deal  to 
do  with  the  effectiveness  of  the  remedy.    As  the  gas  is 
lighter  than  air  and  very  penetrating,  it  would  soon 
escape  and  lose  its  deadly  effect  upon  animal  life  in  a 
building  more  or  less  open. 

2.  The  weather  conditions  have  to  be  considered. 
It  is  not  desirable  under  any  circumstances  to  fumi- 
gate an  enclosure  when  the  wind  is  blowing.    A  calm, 
quiet  day  or  night  should  be  selected  for  the  work. 

3.  The  building  should  be  made  practically  gas- 
tight  by  closing  up  all  the  cracks  and  external  open- 
ings.    This  can  be  done  best  by  pasting  strips  of  ordi- 
nary paper  over  the  cracks.     Special  attention  should 
be  given  to  windows  and  doors,  and  they  should  be 
thoroughly  secured  before  the  gas  is  generated. 

4.  There  should  be  no  lights  or  fire  in  the  build- 
ing while  it  is  filled  with  gas.     It   is  non-explosive 
when  used  according  to  normal  dose  ;  but  to  preclude 
possible  accident  it  is  best  to  be  on  the  safe  side,  thus 
this  suggestion. 

5.  In  a  mill  all   machines,  chests,   spouts,  eleva- 
tors, elevator  legs,  bins,  barrels,  boxes,  etc.,  should 
be   opened,  and  all   unnecessary  material   should   be 
removed  and  burned  before  the  chemicals  are  placed. 


l6o  FUMIGATION   METHODS 

6.  A   door  and   several   windows   or  other   open- 
ings should  be  adjusted  so  they  can  be  opened  from 
the  outside  to  permit   the   escape    of   the   gas   after 
fumigation  is  completed.     Where  convenient  several 
windows  on  each  floor  should  have  .the  top  sash  ar- 
ranged so  they  can  be  lowered  by  means  of  a  rope 
from  the  outside.     In  this  manner  ventilation  is  per- 
fect and  the  gas  soon  escapes. 

7.  A  special  watchman  should  be  detailed  to  look 
after  the  fumigation  and  guard  the  premises  while  the 
gas  is  enclosed  and  after  it  is  released. 

8.  In  buildings  where  several  rooms  or  floors  are 
fumigated  at  the  same  time,  each  room  or  floor  should 
be  shut  off  from  the  other  as  much  as  possible.    Where 
open  stairways  lead  from  one  floor  to  another,  it  will 
be   necessary  to   cover  them   temporarily  with  light 
boards,  over  which  can  be  thrown  old   bags,   sacks, 
blankets,  etc.     Care  should  be  taken  not  to  blockade 
the  stairway  so  the   operator  cannot    readily  escape 
when  the  gas  is  generated.     By  closing  the  doors  be- 
tween the  rooms  and  covering  the  stairways  the  gas  is 
kept  at  a  very  uniform  density  in  each  room  for  a 
longer  period. 

Making  the  gas. — The  chemicals  used  for  making 
hydrocyanic  acid  gas  are  potassium  cyanide,  sulphuric 
acid  and  water.  Special  directions  for  combining  these 
chemicals  for  generating  the  gas  are  given  in  Chapter 
II.  These  instructions  should  be  carefully  studied  and 
followed  specifically,  as  the  process  will  admit  of  no 
guesswork.  The  cautions  cited  should  be  heeded  and 
considered  at  all  times.  The  acid  is  first  placed  in  a 
crock  of  earthenware  or  a  wooden  vessel  and  the  water 


MILLS   AND   OTHER   BUILDINGS  l6l 

poured  upon  it.  The  cyanide  is  afterwards  dropped 
into  the  liquid,  bag  and  all.  The  acid  soon  eats 
through  the  paper  and  a  bubbling  reaction  follows, 
similar  to  that  produced  by  placing  a  piece  of  red-hot 
iron  in  cold  water.  This  lasts  a  few  moments  only, 
or  until  the  acid  acts  upon  the  cyanide. 

A  cloud  of  white  steam  is  almost  instantaneously 
disseminated  throughout  the  room  or  enclosure.  The 
odor  of  this  gas  is  decidedly  that  of  peach  pits,  and  is 
therefore  easily  detected.  It  is  considered  one  of  the 
most  deadly  poisons  known  to  chemical  science  and  is  cer- 
tain death  to  any  animal  inhaling  it.  If  a  person 
should  breathe  his  lungs  full  of  it  he  would  not  live 
to  know  when  he  took  his  second  breath,  if  he  got  it 
at  all.  Attention  has  been  called  to  the  dangerous 
character  of  the  cyanide  and  this  gas  in  each  chapter, 
and  the  writer  again  cautions  those  who  are  interested 
in  the  subject  to  handle  the  material  with  great  care. 
When  so  handled  there  is  no  danger  whatever,  and 
the  results  are  satisfactory  in  every  respect.  The 
effects  on  animal  life  given  in  Chapter  IV.  should  be 
carefully  read  in  this  connection. 

Resisting  power  of  insecJs. — After  much  experi- 
mental work  and  many  practical  tests,  we  have  found 
that  the  most  resistant  insects  infesting  grain  and 
manufactured  products  are  destroyed  when  the  gas  is 
generated  at  the  rate  of  0.25  gramme  cyanide  per 
cubic  foot  of  space  enclosed.  The  adults  of  the  Med- 
iterranean flour  moth,  Ephestia  kuehniclla,  the  Angou- 
mois  grain  moth,  Sitotroga  cerealella,  and  the  Indian 
meal  moth,  Plodia  interpunctella ,  are  destroyed  readily 
with  0.12  to  0.15  gramme  cyanide  per  cubic  foot.  The 


1 62  FUMIGATION   METHODS 

difference  in  the  resisting  powers  of  various  species  of 
insects  is  so  slight  we  generally  recommend  for  indoor 
fumigation  the  use  of  the  0.25  gramme  formula.  Un- 
der no  circumstances  should  a  less  amount  be  used, 
unless  specifically  designated  by  an  expert. 

Some  beetles  require  the  full  strength  to  destroy 
them  in  most  enclosures.  This  is  particularly  true  of 
the  bolting-cloth  beetle,  Tenebroides  mauritanicus ,  and 
its  young,  a  small,  flat,  whitish,  greasy-looking  crea- 
ture, about  one-third  to  one-half  inch  long,  familiar  to 
millers  ;  the  flour  beetle,  Tribolium  confusum,  and  its 
young  ;  the  grain  weevils,  Calandra  granaria  and  C. 
oryza  ;  and  the  American  meal  worm,  Tenebrio  molitor. 
In  fact,  nearly  all  the  beetles  commonly  found  in  mills 
and  other  enclosures  where  farinaceous  foods  are  stored 
or  manufactured  are  not  as  easily  killed  with  the  gas 
as  moths  and  their  young.  Bearing  these  facts  in 
mind,  it  is,  therefore,  best  to  use  the  gas  in  accordance 
with  the  0.25  gramme  formula. 

Estimating  chemicals. — The  amount  of  cyanide 
necessary  for  any  enclosure  is  determined  in  terms  of 
grammes  per  cubic  foot  of  space  enclosed.  To  deter- 
mine the  exact  amount  of  cyanide  necessary  to  fumi- 
gate a  room,  car,  ship,  or  building  of  any  kind,  the 
cubic  contents  must  be  accurately  computed.  As  an 
example,  a  room  20  x  30  x  10  feet  contains  6,000  cubic 
feet  of  air  space.  To  estimate  the  amount  of  cyanide 
required  for  this  enclosure,  multiply  6,000  by  0.25  ; 
thus:  6,000x0.25=  1,500  grammes.  To  reduce  this 
to  ounces,  divide  by  28.35,  as  there  are  28.35  grammes 
in  an  ounce;  thus:  1,500-4-  28.35  =  53  ounces,  the 
exact  amount  of  cyanide  needed  for  the  enclosure.  It 


AND   QTHER   BUILDINGS  163 

is  now  easy  to  determine  the  amount  of  acid  and  water, 
as  a  half  more  acid,  liquid  measure,  than  cyanide,  and 
a  half  more  water  than  acid  are  used;  thus:  53-1-2 
=  26.5,  which,  added  to  53,  equals  79.5  ounces  of  acid, 
or  practically  5  pounds,  liquid  measure.  Again,  79.5, 
or  practically  80,  as  we  usually  discard  fractions, 
divided  by  2  equals  40,  which  added  to  80  makes  120 
ounces  of  water. 

Therefore,  a  room  20  x  30  x  10  feet  requires  53 
ounces,  by  weight,  of  cyanide,  80  ounces,  liquid 
measure,  sulphuric  acid,  and  120  ounces,  liquid  meas- 
ure, water.  The  total  cost  of  chemicals  will  be  about 

$1-25- 

Application. — The  methods  used  for  generating  the 
gas  in  large  enclosures,  such  as  a  mill  or  other  building, 
is  not  unlike  that  illustrated  in  Fig.  70,  Chapter  XIV. 
In  our  early  experimental  work  it  was  thought  desir- 
able to  weigh  the  cyanide  in  bags  of  one  pound  each, 
but  more  recent  practical  tests  have  shown  that 
it  is  more  economical  and  satisfactory  to  have  it 
weighed  out  in  packages  of  three  pounds  each.  Where 
used  in  this  manner  the  jars  or  wooden  vessels  for 
acid  and  water  should  hold  two  or  three  gallons 
each. 

If,  for  example,  we  had  a  room  in  which  18 
pounds  of  cyanide  were  required,  it  would  be  weighed 
out  in  six  packages  of  three  pounds  each.  Each 
package  will  require  a  separate  generator;  therefore, 
six  crocks  or  wooden  vessels  will  be  necessary.  They 
should  be  arranged  at  various  places  in  the  room. 
Strings  should  be  arranged  so  as  to  hang  directly 
over  each  vessel,  and  carried  through  screw-eyes  in 


164 


FUMIGATION   METHODS 


the  ceiling  or  woodwork  to  the  door  or  stairway  lead- 
ing out  of  the  room,  as  shown  in  Fig.  74. 

The  screw-eyes  should  be  firmly  secured,  and  only 
strings  of  good  quality  used.  The  bags  of  cyanide 
should  be  thoroughly  fastened  and  suspended  over  the 


FIG.    74 — DIAGRAM    SHOWING    THE   INTERIOR   ARRANGEMENT   OF 
AN    ENCLOSURE    READY    FOR    FUMIGATION 

vessels  before  the  acid  and  water  are  placed  in  them. 
A  small  wire  hook,  as  shown  in  the  figure,  can 
be  used,  but  a  string  tied  firmly  around  the  neck  of 
the  sack  is  less  trouble  and  more  secure.  With  each 
three-pound  bag  of  cyanide  use  4^  pounds,  liquid 
measure,  sulphuric  acid,  and  6^  pounds  water. 

The  operator  should  begin  on  the  top  floor,  lower 
the  cyanide  into  the  jars  containing  the  acid  and 
water,  quickly  close  the  door  or  other  opening,  and 


MILLS   AND   OTHER   BUILDINGS  165 

get  out.  The  next  story  should  be  handled  in  the 
same  manner  and  the  room  closed.  Kach  floor  below, 
including  the  basement,  is  handled  the  same  way. 
Whenever  the  gas  is  generated  in  a  basement,  cellar, 
or  in  a  room  where  the  operator  can  not  get  out 
quickly  without  climbing  a  ladder  or  going  up-stairs, 
great  care  should  be  taken.  The  lines  of  string  lead- 
ing from  the  cyanide  should  be  arranged  so  they  can 
be  cut  from  a  point  where  the  operator  will  have  no 
difficulty  in  escaping  quickly.  Under  no  circum- 
stances should  one  go  into  a  basement  or  other 
enclosure,  unite  the  chemicals,  and  attempt  to  escape 
by  climbing  a  ladder  or  stair.  Such  a  procedure  would 
be  exceedingly  hazardous  and  should  be  avoided. 

Outside  doors  or  other  openings  in  buildings  where 
persons  are  admitted  should  be  carefully  locked  or 
barred,  so  that  no  one  could  possibly  enter  while  the 
gas  is  enclosed. 

Airing  the  enclosure. — In  buildings  where  large 
quantities  of  grain,  manufactured  products,  or  other 
materials,  are  stored  the  gas  should  be  left,  where  it  is 
convenient  to  do  so,  from  five  to  twenty- four  hours,  or 
even  longer.  During  this  time  more  or  less  of  the  gas 
will  escape,  and  when  the  doors  or  ventilators  are  opened 
great  care  should  be  taken  not  to  inhale  the  escaping 
gas.  The  building  should  be  left  open  and  allowed 
to  thoroughly  air  for  half  an  hour  or  longer  before 
anybody  is  permitted  to  enter  it.  In  tight  enclosures, 
such  as  basements  and  lower  rooms,  where  free 
circulation  is  not  available,  a  longer  time  may  be 
required  to  eliminate  the  gas.  In  such  cases  extra 
precaution  should  be  taken.  If  there  is  the  slightest 


1 66  FUMIGATION   METHODS 

indication  of  the  peach^pit  odor,  the  enclosure  should 
not  be  entered  until  after  it  has  disappeared. 

Residue  in  vessels. — The  material  left  in  the  vessels 
after  fumigation  should  be  handled  carefully.  It  is  an 
excellent  fertilizer,  and  can  be  used  for  that  purpose  if 
composted  with  earth  or  other  material.  Where 
available,  it  can  best  be  utilized  by  throwing  it  upon 
a  manure  pile.  Wash  quickly  in  cold  water,  if  by 
accident  the  acid  is  gotten  upon  the  flesh.  The 
chemical  composition  and  value  of  the  residue  is  given 
fully  in  Chapter  II. 

Cars  and  ships. — Not  infrequently  railroad  coaches, 
street-cars  and  ships  become  badly  infested  and  over- 
run with  vermin  of  various  sorts.  Such  enclosures 
can  be  readily  fumigated  with  hydrocyanic  acid  gas  by 
following  the  directions  given  herewith.  In  South 
Africa  some  railroad  companies  have  found  it 
expedient  to  fumigate  their  passenger  coaches  to 
keep  them  free  from  bedbugs  and  other  pests. 
Very  often  ships  are  overrun  with  cockroaches,  fleas, 
bedbugs,  etc.  The  gas  can  be  supplied  in  such  places 
with  perfect  success  for  the  total  destruction  of  the 
vermin.  In  any  case  whatever  enclosure  is  to  be 
fumigated  the  same  precautions  and  methods  for 
handling  and  generating  this  gas  should  be  observed. 

Dwelling-houses  and  storerooms.  — This  gas  can  also 
be  used  with  perfect  safety  in  the  hands  of  an  expert 
in  dwelling-houses  or  storerooms  infested  with  the 
ordinary  household  pests.  In  such  cases,  however, 
great  care  should  be  taken  in  handling  the  material, 
and  no  person  should  be  allowed  to  remain  in  the 


MILLS  AND   OTHER   BUILDINGS  167 

house  during  the  process  of  fumigation.  It  has  re- 
cently been  applied  in  a  room  of  the  Division  of 
Botany,  United  States  Department  of  Agriculture,  by 
W.  R.  Beattie,  for  the  destruction  of  cockroaches.  He 
recommends  the  use  of  the  gas  at  the  rate  of  o.io  to 
0.22  gramme  cyanide  per  cubic  foot  for  the  destruc- 
tion of  flies,  cockroaches,  moths,  etc.  For  fleas  and 
bedbugs  the  writer  has  found  that  a  dose  varying  from 
0.20  to  0.22  gramme  cyanide  per  cubic  foot  is  far  more 
desirable. 

This  method  will  be  found  very  useful  in  clearing 
large  hotels,  dwelling-houses  and  other  buildings  used 
as  summer  resorts  of  undesirable  pests.  The  gas 
should  be  applied  at  a  time  when  the  buildings  are 
not  occupied.  On  account  of  its  very  rapid  diffusion, 
from  three  to  twenty-four  hours  will  accomplish  the 
desired  results.  No  fumigation  for  less  than  three 
hours  is  recommended  for  household  pests.  Under  no 
circumstances  should  it  be  used  in  a  house  or  other 
building  occupied  by  other  individuals,  either  above, 
below,  or  on  either  side  of  the  room  or  apartment 
fumigated.  The  gas  will  in  no  way  injure  any  article 
of  furniture  found  in  the  ordinary  household,  Care 
should  be  taken,  however,  to  remove  all  edible  mate- 
rials. Water  used  for  drinking  should  not  be  left  in 
the  room.  The  gas  should  not  be  handled  by  persons 
who  are  not  thoroughly  familiar  with  its  deadly  na- 
ture. It  is,  therefore,  not  generally  recommended  for 
use  in  houses  unless  applied  by  an  expert. 

Explosive  properties. — In  all  our  experiments  and 
recommendations  we  have  kept  the  amount  of  potas- 
sium cyanide  considerably  below  the  danger  limit,  so 


1 68  FUMIGATION   METHODS 

far  as  combustion  is  concerned.  The  gas  is  non-ex- 
plosive when  used  at  or  below  0.25  gramme  potassium 
cyanide  per  cubic  foot  of  space  enclosed,  other  condi- 
tions being  normal.  We  have  asked  Dr.  H.  W. 
Wiley,  Chief  of  the  Bureau  of  Chemistry,  United 
States  Department  of  Agriculture,  for  his  opinion  re- 
garding this  matter,  and  quote  the  following  letter 
from  him  : 

"Cyanogen  gas,  or  hydrocyanic  acid  gas,  mixed 
with  air  or  oxygen,  forms  an  explosive  mixture,  but  I 
should  not  think  that  in  the  proportions  you  mention, 
viz.,  0.25  gramme  of  potassium  cyanide  for  each  cubic 
foot  of  air  space,  it  would  produce  an  atmosphere 
which  would  be  explosive.  Hydrocyanic  acid,  how- 
ever, is  combustible  and  could  be  mixed  with  air,  I 
presume,  so  as  to  form  an  explosive  mixture.  I  have 
looked  over  the  authorities,  but  can  find  no  mention 
of  explosive  properties. 

' '  The  danger  of  hydrocyanic  acid,  in  my  opinion,  is 
not  from  its  explosive  properties,  but  from  its  highly  poi- 
sonous nature.  Small  quantities  of  hydrocyanic  acid 
gas  inhaled  are  extremely  poisonous,  and  are  apt  to 
produce  fatal  results.  //  would  be  equivalent  to  instant 
death  for  any  one  to  enter  a  building  filled  with  it. 

' '  While  I  do  not  think  there  would  be  danger  of 
an  explosion  in  the  proportions  you  mention  (0.25 
gramme),  I  would  advise  great  circumspection  in  the 
introduction  of  a  light,  unless  it  be  an  incandescent 
electric  light,  enclosed  in  an  air-tight  globe.  Such 
lights  should  always  be  used  where  there  is  any  danger 
of  explosion. ' ' 

Practical  application. — The   following   testimonials 


MILLS   AND   OTHER   BUILDINGS  169 

from  a  large  number  of  individuals  throughout  the 
country,  who  have  used  hydrocyanic  acid  gas  in  mills, 
warehouses,  elevators  and  other  places,  are  sufficient 
to  corroborate  the  statement  that  it  is  of  very  great 
economic  value  when  used  in  such  places.  In  quot- 
ing these  letters  all  reference  to  individual  and  firm 
names  has  been  omitted  purposely.  The  following  is 
a  letter  from  a  Utah  milling  firm  who  used  this  gas 
recently  : 

We  procured  the  necessary  chemicals  and  proceeded 
to  carry  out  your  instructions  specifically.  We  believe 
that  we  are  safe  in  saying  that  the  experiment  was 
entirely  successful,  (i)  because  on  leaving  the  build- 
ing, after  dropping  the  chemicals  into  the  water  and 
acid,  we  heard  the  bubbling  described  by  you,  thus 
proving  that  action  took  place  between  the  cyanide 
and  the  adulterated  acid;  (2)  when  we  opened  the 
door  of  the  building,  after  leaving  it  closed  as  directed, 
two  dead  pigeons  were  found  (we  had  placed  them 
in  the  building  purposely),  the  gas  had  entirely  filled 
the  enclosure,  as  the  two  birds  were  in  different 
places  in  the  rooms;  and  (3)  the  best  proof  that 
the  experiment  was  successful  is  the  fact  that  we 
cannot  find  any  trace  of  the  pests  which  formerly 
existed,  even  though  warm  weather  is  here.  We 
wish  again  to  thank  you  for  the  interest  taken  in  this 
matter,  as  well  as  the  favors  extended  to  us. 

Tobacco  warehouse. — The  writer  personally  con- 
ducted the  fumigation  of  a  five-story  brick  building  in 
Baltimore,  September  18,  1900,  infested  with  insects 
{Lasioderma  serricorne},  injuring  leaf  tobacco  in  store, 
and  the  method  was  thoroughly  successful.  Fifty 


1 70  FUMIGATION   METHODS 

pounds  of  cyanide  wei^  used  in  this  building  at  one 
time.  The  four  upper  stories  were  fumigated  first, 
and  a  few  days  later  the  basement  and  first  floors. 
We  demonstrated  that  this  gas  can  be  used  even  in  the 
heart  of  a  solidly  built-up  city  block  if  properly 
handled.  The  building  in  question  is  located  in  the 
heart  of  the  business  center  of  the  city.  Bvery  crack 
about  the  windows  was  pasted  up  with  narrow  strips 
of  paper.  We  used  string  and  bags,  suspending  3^ 
pounds  of  cyanide  over  each  four-gallon  jar.  We  had 
six  jars  each  on  the  second  and  third  floors  and  two 
each  on  the  fourth  and  fifth  floors.  The  gas  was  gen- 
erated after  office  hours  at  7.30  and  the  windows  were 
lowered  from  the  outside  about  12  o'clock,  midnight, 
the  same  night.  The  windows  in  the  fifth  story  were 
lowered  first,  and  by  opening  a  door  below  a  draft  was 
created  through  the  elevator  shaft  carrying  the  bulk 
of  the  gas  out  above  the  building.  The  other  windows 
were  opened  a  few  minutes  later  and  the  building 
aired  the  rest  of  the  night,  one  man  remaining  on 
guard  all  the  time.  The  results  were  very  gratifying. 
The  pests  were  thoroughly  destroyed,  and  in  addition 
seven  dead  rats  were  found  on  the  basement  floor  and 
one  on  the  third  floor. 

Mills  and  elevators. — The  following  is  from  a  Cana- 
dian firm :  In  connection  with  our  use  of  hydro- 
cyanic acid  gas  for  the  extermination  of  the  Mediter- 
ranean flour  moth,  we  beg  to  report  the  following : 
The  cubic  contents  of  our  buildings  figure  290,472 
cubic  feet,  for  which  we  used  151  pounds  cyanide  of 
potassium,  226  pounds  sulphuric  acid,  and  338  pounds 
water.  We  distributed  150  crocks  throughout  the 


MILLS   AND   OTHER   BUILDINGS  1 71 

buildings,  as  directed  by  you,  putting  about  an  equal 
number  on  each  floor,  and  into  each  crock  we  put  i  >^ 
pounds  sulphuric  acid  and  2^  pounds  water.  We 
then  weighed  out  151  pounds  of  cyanide  and  put  this 
up  in  manila  bags  of  i  pound  each  ;  each  bag  was 
tied  with  a  string,  upon  which  was  left  a  loop.  We 
placed  screw-hooks  into  different  parts  of  the  wood- 
work, spouts,  elevator  legs,  etc.,  passed  through  the 
hooks  stout  twine,  so  arranged  that  it  would  come 
directly  over  the  center  of  each  crock.  Just  where  the 
string  passed  over  the  crock  we  tied  an  S-hook,  on 
which  we  hung  the  bags  of  potassium. 

The  stairways  leading  from  the  basement  to  the 
top  of  our  mill  go  up  at  the  side  and  nearly  at  the  end 
of  the  building,  one  stair  directly  above  the  other. 
At  the  side  and  the  ends  of  the  mill  farthest  from  the 
stairway  we  started  six  different  lines  of  string,  tying 
one  end  of  each  line  to  the  opposite  wall,  and  leading 
each  string  to  the  stairway  by  a  different  route  over 
the  floor  and  tying  each  string  tightly  to  the  stairway 
rail.  At  the  proper  moment  all  the  strings  on  the 
floor  could  be  cut  at  the  same  time,  and  all  the  little 
bags  of  cyanide  would  fall  immediately  into  the  solu- 
tion of  acid  and  water. 

Each  opening  at  the  stairs  had  been  provided 
with  a  tight  door.  The  man  who  cut  the  strings 
started  at  the  top  floor,  worked  downward,  cutting 
the  strings  on  each  floor  as  he  passed  through  and 
closing  the  door  behind  him  quickly,  so  that  it  was 
impossible  for  even  a  whiff  of  the  gas  to  reach  him. 

We  cut  these  strings  at  8  o'clock  Saturday  night 
and  placed  a  man  on  guard  all  night.  The  odor 


172  FUMIGATION    METHODS 

of  the  gas  was  quite,  noticeable  twelve  feet  away 
from  the  mill,  although  every  precaution  had  been 
taken  to  close  all  the  cracks  by  pasting  strips  of 
paper  around  the  window-sash  and  door-frames,  and 
otherwise  making  the  mill  as  tight  as  possible.  We 
opened  the  building  at  9  o'clock  Monday  morning 
and  could  not  detect  more  than  the  faintest  odor  of 
the  gas.  A  careful  examination  showed  the  floor 
plentifully  sprinkled  with  moths,  flies,  spiders,  and 
occasionally  a  mouse  or  two.  We  examined  care- 
fully for  the  grubs  or  larvae  and  found  plenty  of  them 
dead,  and  but  two  or  three  alive  in  a  mass  of  flour, 
but  these  were  not  by  any  means  lively.  We  have 
watched  carefully  ever  since,  over  two  months,  and 
have  seen  only  an  occasional  moth.  We  believe  it 
is  impossible  to  find  a  moth  in  our  two  buildings 
to-day. 

We  are  delighted  with  the  results  of  this  gas.  In 
our  case  it  has  certainly  been  a  decided  success.  We 
would  say  to  any  one  intending  to  use  it  they  should 
take  every  precaution  to  have  the  manila  bags  of  good 
quality.  The  cyanide  of  potassium  liquidizes  after 
being  placed  in  the  bags  and  exposed  to  the  air.  It  is 
apt  to  drop  into  the  solution  by  the  bag  becoming  wet 
and  tearing  at  the  bottom  before  the  strings  are  ready 
to  be  cut.  In  conclusion,  we  wish  to  express  our 
hearty  appreciation  of  your  painstaking  care  in  the 
instructions  of  the  use  of  this  gas  and  also  for  your 
personal  letters  to  us  with  regard  to  certain  particulars. 

The  following  report  is  from  a  Western  miller : 
After  carefully  reading  your  instructions  and  closely 
following  them,  we  fumigated  a  i5o-barrel  mill  with 


MIU<S   AND   OTHER    BUILDINGS  173 

marked  success.  We  allowed  the  gas  to  remain  in  the 
building  one  night  and  day.  The  next  morning  we 
found  everything  had  perished,  including  many  mice 
and  weevil.  The  last  day  or  so  we  have  noticed  one 
or  two  weevil,  probably  some  that  survived  by  being 
deeply  buried  in  cracks.  We  can  certainly  speak  a 
good  word  for  the  remedy,  and  thank  you  very  much 
for  your  instructions,  which  has  aided  us  in  free- 
ing our  mill  and  warehouse  from  such  troublesome 
pests. 

Repeated  applications  demonstrated  that  the  remedy 
is  one  that  can  be  relied  upon  when  properly  used. 
An  occasional  miller,  however,  may  get  a  bad  lot  of 
chemicals  and  can  not  generate  the  gas  properly.  One 
of  our  Canadian  friends  wrote  recently  that  he  was  not 
very  successful  in  his  fumigation,  stating  that  the 
cyanide  did  not  work  in  the  acid  and  water.  It  was 
apparent  to  me  he  had  used  an  old  grade  of  cyanide, 
about  58  per  cent,  purity,  where  he  should  have  had 
the  chemically  pure  cyanide,  guaranteed  98  to  99  per 
cent.  My  suspicions  were  well  founded,  and  a  few 
days  later,  at  my  suggestion,  he  tried  the  pure  cyanide 
with  good  results  and  wrote  me  as  follows  August  15: 

Your  letter  of  July  22  was  duly  received  and  care- 
fully noted.  About  ten  days  ago  we  fumigated  again 
with  the  hydrocyanic  acid  gas,  and  this  time  with 
complete  success,  hardly  a  bug  or  grub  of  any  kind 
being  left  alive.  We  see  an  odd  one  occasionally,  both 
moth  and  weevil,  and  we  expecl;  there  will  be  some 
hatched  out  from  eggs  left.  We  shall  fumigate  again 
in  another  month  or  so  if  necessary.  The  fumigation 
is  so  simply  done,  and  so  deadly,  that  we  have  now  no 


174  FUMIGATION   METHODS 

fear  but  what  we  can  keep  our  mill  free  in  the  future. 
We  removed  all  flour,  with  exception  of  a  few  samples, 
but  on  these  we  could  discover  no  taint.  Our  failure 
before  was  owing  to  inferior  cyanide,  just  as  you  said, 
and  was  our  chemist's  fault  entirely.  We  again  thank 
you  for  your  advice  and  information. 

Successful  application  in  house  and  laboratory. — The 
writer,  knowing  that  Dr.  H.  J.  Webber,  of  the  United 
States  Department  of  Agriculture,  who  is  in  charge  of 
the  Laboratory  of  Plant  Breeding,  had  used  hydro- 
cyanic acid  gas  successfully  in  a  dwelling-house,  wrote 
him  for  an  account  of  his  experience  and  received  the 
following  reply  : 

' '  I  had  one  experience  in  Florida  in  fumigating  a 
rented  house  for  various  household  vermin.  While 
such  a  matter  is  usually  considered  strictly  a  private 
affair,  I  have  no  objection  to  giving  you  the  following 
brief  note  :  While  living  in  Florida  we  moved  into  a 
house  which  was  found  to  be  infested  with  cockroaches 
and  bedbugs.  In  order  to  rid  the  place  of  these  pests 
it  was  fumigated  with  hydrocyanic  acid  gas,  using  one 
ounce  of  potassium  cyanide  to  each  100  cubic  feet  of 
space  in  the  house.  The  fumigation  was  started  very 
early  in  the  morning  and  continued  for  about  six 
hours,  when  the  windows  and  doors  were  opened  and 
the  rooms  thoroughly  ventilated.  The  house  was 
occupied  that  night  as  usual,  there  being  only  a  slight 
odor  of  the  cyanide  perceptible.  The  effect  of  this 
fumigation  was  marvelous.  I  have  never,  before  or 
since,  seen  a  house  so  thoroughly  cleared  of  insects. ' ' 

In  the  same  letter  Dr.  Webber  says  they  were 
greatly  bothered  last  summer,  in  their  Washington 


AND   OTHER    BUILDINGS  175 

laboratory,  with  cockroaches,  the  so-called  "silver 
fish,"  and  the  Angoumois  grain  moth.  C.  P.  Hartley, 
an  assistant  in  the  laboratory,  had  the  building  fumi- 
gated with  very  excellent  results.  At  the  suggestion 
of  Dr.  Webber  the  following  statement  of  facts  was 
furnished  by  Mr.  Hartley  : 

' '  During  the  summer  of  1901  one  of  the  laboratories 
of  the  United  States  Department  of  Agriculture  became 
badly  infested  with  mice  and  insects  of  many  kinds. 
It  was  decided  to  try  the  efficacy  of  hydrocyanic  acid 
gas  in  ridding  the  building  of  these  pests.  This  labora- 
tory had  become  the  abode  of  cockroaches,  beetles, 
crickets,  moths,  flies,  etc.,  to  some  extent  because  it 
was  connected  with  greenhouses  where  these  insects 
abounded,  but  more  especially  because  of  seeds,  fruits, 
and  plant  specimens  that  were  stored  in  the  vari6us 
rooms.  The  entire  building,  a  two-story  frame  struc- 
ture of  eight  rooms,  was  twice  fumigated  during  the 
latter  part  of  the  summer  with  such  success  that  the 
building  was  free  from  insects  for  the  rest  of  the  year. 
The  first  fumigation  was  given  the  latter  part  of 
August  and  freed  the  building  for  a  week  or  more, 
after  which  time  many  small  roaches  and  other  young 
insects  became  noticeable  which  probably  developed 
from  eggs  in  the  building. 

*  *  For  the  first  fumigation  old  stock  potassium 
cyanide  from  several  sources  and  of  various  appear- 
ances was  used,  but  for  the  second,  ten  days  later, 
fresh  material  was  used,  and  resulted  in  killing  every 
insect  and  mouse  in  the  building.  This  fumigation 
was  started  at  four  o'clock  in  the  evening  and  the 
building  was  kept  closed  until  the  next  morning,  when 


1 76  FUMIGATION  METHODS 

it  was  opened  and  occupied  during  the  day.  The  only 
injurious  effects  of  the  gas  were  on  the  mice  and  in- 
sects in  the  building,  but  the  precaution  had  been  taken 
to  remove  the  unused  printing  paper  and  dry  plates 
before  the  fumigation,  although  it  is  not  definitely 
known  that  they  would  have  been  injured  by  the  gas. 
The  morning  after  the  fumigation  dead  insects  were 
found  lying  everywhere  about  the  building:  flies  had 
dropped  from  the  ceilings  and  windows,  and  mice  had 
come  from  their  hiding-places  and  died. 

11  For  each  fumigation  one-tenth  (o.i)  of  a  gramme 
of  potassium  cyanide  was  used  for  each  cubic  foot  of 
space  in  the  building.  All  the  connecting  doors  were 
opened.  Four  stone  jars  were  placed  one  at  each  end 
of  the  building  on  the  two  floors.  No  exact  measure- 
ment was  made  of  the  strength  and  quantity  of  acid, 
but  an  attempt  was  made  to  use  about  the  same  weight 
of  commercial  sulphuric  acid  as  of  potassium  cyanide. 
The  commercial  acid  was  diluted  by  pouring  it  into 
the  water  which  was  placed  in  the  jars  first.  The 
cyanide  was  then  dropped  into  the  mixture  while  still 
hot  and  the  building  at  once  closed  for  the  night. ' ' 


CHAPTER  XVII 
GRAINS  AND   OTHER  SEEDS 

N  view  of  the  fact  that  hydrocyanic  acid  gas  is 
being  universally  used  as  a  fumigant  for  the 
destruction  of  insects  in  grain  and  seeds  stored 
in  various  enclosures,  it  became  necessary  to 
know  how  this  gas  would  affect  edible  and  germinating 
properties  of  the  grain.  Conclusive  and  detailed 
results  were  obtained  by  Dr.  Charles  O.  Townsend, 
now  Pathologist  in  the  U.  S.  Department  of  Agricul- 
ture. The  work  was  done  in  connection  with  the 
Maryland  State  Horticultural  Department  while  he 
was  State  Pathologist.  The  methods  employed  in 
these  experiments  consisted  simply  in  placing  the  seeds 
to  be  tested  in  air-tight  chambers  and  then  generating 
the  desired  amount  of  gas.  In  the  first  experiments 
air-tight  boxes  of  several  cubic  feet  capacity,  such 
as  are  used  by  nurserymen,  were  employed.  In  these 
various  experiments  the  gas  was  generated  in  the  same 
manner  as  for  nursery  stock.  In  later  experiments 
Dr.  Townsend  used  large  glass  bell- jars.  The  jars  were 
so  arranged  that  the  gas  could  be  generated  and  kept 
within  them  for  any  length  of  time  with  the  seeds. 

The  seeds  used  were  mostly  corn,  wheat,  beans  and 
clover.  Occasionally  other  seeds  were  used,  but  those 
mentioned  were  carried  through  all  the  experiments 
and  fairly  represent  the  common  grains  and  other  seeds. 
Some  seeds  under  certain  conditions  seem  to  be  more 


178  FUMIGATION   METHODS 

sensitive  to  treatment  t^an  others,  but  the  behavior  in 
general  did  not  vary  much.  The  strength  of  the  gas 
used  varied  from  0.003  °f  a  gramme  per  cubic  foot  to 
1.45  grammes  per  cubic  foot.  In  the  first  experi- 
ment Dr.  Townsend's  obje<5l  was  to  determine  whether 
the  ordinary  strength  of  gas  used  in  fumigation 
would  be  harmful  to  the  seeds.  In  later  experiments 
he  determined  the  maximum  and  minimum  strength 
of  gas  that  seeds  could  resist  under  varying  condi- 
tions. 

Time  is  an  important  factor  in  this  work.  Nursery 
stock  must  be  fumigated  30  to  45  minutes  or  longer 
to  destroy  all  insect  life,  but  in  the  fumigation  of  build- 
ings in  which  large  bulks  of  grain  are  stored,  time  must 
be  allowed  for  the  gas  to  penetrate  the  mass.  During 
this  period  the  grain  on  the  surface  is  exposed  to  the 
influence  of  the  gas  from  the  time  it  is  generated.  To 
determine  the  shortest  and  longest  time  required  for 
grain  to  respond  to  the  influence  of  the  various 
strengths  of  gas  under  different  conditions  employed, 
the  exposures  varied  from  one  hour  to  one  year. 
Seeds  were  also  fumigated  under  varying  conditions, 
some  being  used  while  perfectly  dry  in  a  dry  chamber, 
while  others  were  used  after  being  soaked  in  water, 
and  still  others  were  soaked  and  placed  in  a  moist 
atmosphere  filled  with  gas.  After  considering  all  the 
facts  Dr.  Townsend's  conclusions  are  concise,  clear  and 
practical. 

He  found  that  seeds,  whether  in  the  dry  or  moist  con- 
dition, are  capable  of  absorbing  hydrocyanic  acid  gas 
from  the  surrounding  atmosphere,  whether  the  amount 
of  gas  in  the  atmosphere  is  large  or  small  per  cubic  foot. 


GRAINS  AND   OTHER  SEEDS  179 

The  gas  thus  absorbed  has  a  marked  influence  upon 
the  germination  of  the  seeds  and  upon  the  subsequent 
growth  of  the  seedlings.  In  these  experiments  it  was 
found  that  some  of  the  seeds  were  able  to  resist  for 
more  than  three  hours  the  influence  of  the  gas  from 
0.25  gramme  of  potassium  cyanide  per  cubic  foot,  al- 
though after  three  hours  50  per  cent,  of  the  seeds  were 
unable  to  germinate  and  the  other  half  were  held  in 
check  for  forty-eight  hours  beyond  the  usual  time  of 
germination.  However,  the  seeds  that  did  germinate 
produced  seedlings  that  grew  at  the  normal  rate.  If 
the  grains  or  seeds  are  dry,  the  influence  of  the  gas  is 
far  less  marked  than  if  they  are  moist,  and  the  drier 
they  are,  the  less  they  are  influenced  by  the  gas. 

It  would  seem,  therefore,  that  the  gas  exerts  its  in- 
fluence through  the  medium  of  the  moisture  contained 
in  the  seeds  and  in  the  seedlings.  Even  in  older  plants 
it  is  the  more  succulent  parts  that  are  most  readily  af- 
fected by  the  gas.  The  seed-coats  serve  more  or  less 
as  a  protection  for  the  inner  seed  parts,  and  as  soon  as 
the  seedlings  escape  from  the  seed-coats  they  are  more 
seriously  affected  by  the  gas,  and  if  the  charge  is  suf- 
ficiently strong  the  seedlings  refuse  to  grow  almost  as 
soon  as  they  leave  the  seed-coats.  Dry  seeds  are  suf- 
ficiently resistant  to  the  influence  of  hydrocyanic  acid 
gas  to  be  treated  for  several  weeks  with  an  atmosphere 
saturated  with  the  gas  without  destroying  their  vital- 
ity. It  would  be  impossible,  however,  to  preserve 
even  dry  seeds  indefinitely  in  any  strength  of  the  gas, 
since  it  eventually  penetrates  the  dry  seeds  and  im- 
pairs and  finally  destroys  the  vitality  of  the  seeds.  If 
the  seeds  are  damp  they  are  much  more  susceptible  to 


180  FUMIGATION   METHODS 

the  influence  of  the  ga»,  and  should  not  remain  more 
than  two  or  three  hours  in  gas  of  sufficient  strength  to 
destroy  animal  life. 

Dry  seeds. — Only  a  few  experiments  have  been 
performed  along  this  line,  but  probably  a  sufficient 
number  to  determine  the  point  in  question,  viz., 
whether  dry  seeds  treated  with  hydrocyanic  acid  gas 
retain  enough  of  the  gas  to  make  them  injurious  to 
animal  life.  Grain  was  subjected  to  gas  of  different 
strengths,  and  for  longer  or  shorter  periods  of  time, 
varying  from  one  to  sixty  days.  Grains  thus  treated 
were  from  time  to  time  fed  to  mice  that  had  been 
caught  without  injury,  and  placed  in  glass  cages  so 
that  they  could  be  observed  constantly.  The  cages 
were  provided  with  an  abundant  supply  of  air  and 
water,  and  kept  at  ordinary  normal  temperature  of  the 
laboratory  where  the  mice  had  been  living  previous  to 
the  beginning  of  the  experiment.  Occasionally  the 
mice  began  eating  the  grains  as  soon  as  they  wrere 
placed  within  reach,  but,  as  a  rule,  several  minutes  to 
several  hours  elapsed  between  the  time  the  grains  were 
taken  from  the  hydrocyanic  acid  gas  and  the  time  they 
were  eaten  by  the  mice,  thus  giving  time  for  any  gas 
that  remained  in  contact  with  the  seed  or  that  had 
penetrated  the  seed-coat  to  escape  into  the  amosphere. 

In  one  instance,  for  example,  a  mouse  was  fed  one 
dozen  kernels  of  corn  and  three  dozen  grains  of  wheat 
that  had  been  for  four  and  one-fourth  days  in  an  at- 
mosphere containing  gas  from  one  gramme  of  potas- 
sium cyanide  per  cubic  foot.  The  mouse  began  eating 
the  grain  at  once,  and  at  the  end  of  twenty-four  hours 
had  eaten  the  whole  of  five  grains  of  corn  and  had 


GRAINS   AND   OTHER   SEEDS  l8l 

eaten  the  chit  out  of  five  other  grains.  It  had  also 
eaten  fourteen  grains  of  wheat  and  had  eaten  the  chit 
of  eleven  others  without  injury.  Several  similar  ex- 
periments were  carried  through  with  like  results. 
Hence  it  seems  safe  to  conclude  that  dry  grains  treated 
for  several  days  with  hydrocyanic  acid  gas  of  sufficient 
strength  to  destroy  insect  pests  that  may  be  in  the 
grain  will  in  no  way  poison  the  grain,  and  it  may  there- 
fore be  used  for  food  without  injury. 

Damp  seeds. — The  damp  seeds  were  soaked  for 
twenty-four  hours  and  then  treated  with  gas  in  the 
same  manner  as  in  the  preceding  experiments  and  were 
kept  in  the  gas  for  different  periods  of  time  varying 
from  several  hours  to  several  days  in  the  different  ex- 
periments. Here,  as  in  the  germination  experiments, 
we  find  that  moisture  has  a  decided  influence  upon 
the  ability  of  the  grains  to  absorb  gas,  i.e.,  after  soak- 
ing some  corn  and  wheat  for  twenty-four  hours  in 
water  and  then  leaving  for  forty-eight  hours  in  the  gas 
obtained  from  one  gram  of  potasium  cyanide  per  cubic 
foot,  a  mouse  in  apparently  good  health  was  given 
twelve  grains  of  corn  and  thirty-six  grains  of  wheat. 
The  mouse  began  eating  at  once  and  ate  the  chit  out 
of  one  kernel  of  corn  and  began  eating  a  second  ker- 
nel when  he  suddenly  became  stupid  and  was  unable 
to  walk  without  staggering.  That  the  mouse  was 
hungry  is  evidenced  by  the  fact  that  it  began  eating  as 
soon  as  the  grain  was  placed  in  the  cage  and  from  the 
fact  that  it  had  been  given  but  little  food  on  the  pre- 
ceding day  for  the  purpose  of  having  it  hungry  enough 
to  begin  at  once  on  the  grain  as  soon  as  it  was  removed 
from  the  gas.  Although  the  mouse  lived  for  several 


1 82  FUMIGATION   METHODS 

hours,  it  eventually  died  apparently  from  the  effects 
of  the  small  amount  of  grain  eaten,  as  it  did  not  eat 
any  more  of  either  kernel  of  grain  nor  would  it  eat 
cheese  or  any  other  material  placed  before  it. 

In  general  it  was  found  that  if  the  mice  ate  the 
damp  grain  immediately  after  taking  it  from  the  gas 
they  became  stupid  and  eventunlly  died  from  the 
effects.  If,  however,  the  grain  was  allowed  to  remain 
for  a  time  out  of  the  gas  before  it  was  eaten,  no  ill 
effects  seemed  to  be  produced,  although  the  grain  did 
not  seem  to  return  to  its  normal  condition,  as  it  was 
never  eaten  readily  after  it  became  perfectly  dry. 
When  the  mice  could  be  induced  to  eat  it,  as  they 
were  in  several  instances,  it  did  not  seem  at  all  injuri- 
ous. It  may  be  concluded,  therefore,  that  the  fumi- 
gation of  dry  grains  with  hydrocyanic  acid  gas  does 
not  in  any  way  injure  the  grain  for  food  purposes. 
And  even  if  the  grain  is  damp,  it  will  not  be  made  in- 
jurious for  food,  if -it  is  allowed  to  air  for  a  short  time 
after  fumigating  before  it  is  prepared  for  use. 

Summary. — In  brief,  Dr.  Towsend  has  clearly 
summed  up  the  results  of  his  work  in  the  following 
paragraphs: 

Stored  grains  and  other  seeds  may  be  fumigated  with 
hydrocyanic  acid  gas  of  required  strength  and  for 
sufficient  time  to  insure  the  destruction  of  insect  pests 
without  injury  to  the  germinating  quality  of  the  seeds 
and  without  rendering  them  injurious  as  foods. 

Dry  grains  and  other  seeds  may  be  fumigated  with 
the  usual  strength  of  hydrocyanic  acid  gas  for  several 
days  without  in  any  way  interfering  with  the  germi- 
nating property  of  the  seeds. 


GRAINS  AND  OTHER  SEEDS  183 

Dry  grains  and  other  seeds  treated  for  several  days 
with  hydrocyanic  acid  gas  of  any  strength  will  not  be 
injured  for  food. 

Dry  grains  and  other  seeds  may  be  subjected  for 
several  months  to  the  influence  of  hydrocyanic  acid  gas 
at  the  rate  of  one  gramme  or  less  of  potassium  cyanide 
per  cubic  foot  without  entirely  destroying  the  ability 
of  the  seeds  to  germinate. 

Dry  grains  and  other  seeds  subjected  to  the  influence 
of  hydrocyanic  acid  gas  derived  from  one  gramme  of 
potassium  cyanide  per  cubic  foot  will  lose  their  germi- 
nating ability  at  the  expiration  of  eight  months,  while 
the  same  seeds  subjected  to  the  gas  from  one-third  of  a 
gramme  of  potassium  cyanide  per  cubic  foot  will 
retain  their  vitality  until  the  expiration  of  twelve 
months. 

Dry  grains  and  other  seeds  subjected  for  from  fifteen 
to  sixty  days  to  the  influence  of  hydrocyanic  gas  from 
one-third  to  one  gramme  of  potassium  cyanide  per 
cubic  foot  will  hasten  germination  and  accelerate  the 
growth  of  the  resulting  seedlings.  Although  the 
acceleration  continues  for  several  days  it  does  not  seem 
to  be  of  sufficient  duration  and  degree  to  be  of  any 
practical  value. 

Damp  grains  and  other  seeds  are  much  more  sensi- 
tive to  the  influence  of  hydrocyanic  acid  gas  than  dry 
seeds. 

Grains  and  other  seeds  soaked  twenty-four  hours  or 
more  will  not  germinate  in  gas  stronger  than  three- 
thousandths  of  a  gramme  of  potassium  cyanide  per 
cubic  foot,  whereas  if  the  seeds  are  soaked  but  twelve 
hours,  they  are  able  to  germinate  in  an  atmosphere 


1 84  FUMIGATION  METHODS 

containing  hydrocyanic^cid  gas  from  fifty-thousandths 
of  a  gramme  of  potassium  cyanide  per  cubic  foot  and 
in  much  less  time  than  when  soaked  for  twenty-four 
hours. 

Grains  and  other  seeds  soaked  for  twenty-four  hours 
and  then  left  for  seven  days  in  an  atmosphere  of  hydro- 
cyanic acid  gas  will  remain  inactive  while  in  the  gas 
and  from  seven  to  twelve  days  after  removal,  but  will 
eventually  germinate  to  some  extent  if  the  strength  of 
gas  used  does  not  exceed  fifty-thousandths  of  a  gramme 
of  potassium  cyanide  per  cubic  foot,  i.e. ,  hydrocyanic 
acid  gas  is  capable  of  holding  seeds  in  an  inactive  state 
for  two  weeks  or  longer  without  destroying  their  vital- 
ity, even  when  the  conditions  are  otherwise  favorable 
for  germination. 

Damp  grains  and  other  seeds  treated  with  hydrocy- 
anic acid  gas  of  any  strength  even  for  short  periods  of 
time  should  not  be  used  for  food  until  several  hours 
after  removing  from  the  gas.  The  effect  of  the  gas 
eventually  passes  off  and  the  grain  may  be  eaten  with 
safety,  although  long  exposure  to  the  gas  seems  to 
render  it  unpalatable. 

In  the  first  experiments  conducted  by  the  writer, 
where  grain  and  manufactured  products  were  stored, 
the  gas  was  generated  at  the  rate  of  o.  10  to  0.12 
gramme  per  cubic  foot.  Very  satisfactory  results  were 
secured,  but  further  experiments  showed  that  it  was 
better  to  use  from  0.20  to  0.25  gramme  per  cubic  foot 
of  space  enclosed.  It  was  found  that  a  greater  volume 
of  gas  remained  in  the  building  for  a  longer  time 
where  larger  doses  were  used.  At  the  same  time  no 
deleterious  effects  were  observed  either  in  the  manu- 


GRAINS  AND  OTHER  SEEDS  185 

factured  products  or  the  grain  in  storage.  Repeated 
applications  of  this  gas  in  mills,  elevators,  and  other 
enclosures  with  the  0.25  gramme  formula  has  proven 
that  this  is  one  of  the  most  effective  and  satisfactory 
remedies  for  the  destruction  of  insedls  and  vermin  in 
such  places  now  known. 


- 

CHAPTER  XVIII 
DIFFUSION  OF   HYDROCYANIC  ACID  VAPOR 


I 


N  a  recent  report  (twelfth)  of  the  Delaware  Agri- 
cultural Experiment  Station,  Prof.  Charles  L<. 
Penny  gives  the  results  of  a  careful  series  of 
experiments  to  determine  the  diffusion  of 
hydrocyanic  acid  vapor  in  an  enclosed  space,  from 
which  the  following  facts  are  abstracted  or  quoted:  In 
all  the  diffusion  experiments,  in  both  small  boxes  and 
large  rooms,  a  uniform  charge  of  chemicals  was  used. 
For  each  cubic  foot  of  space  to  be  filled  with  o.  2  gramme 
potassium  cyanide,  0.45  c.  c.  water,  and  0.3  c.  c.  of  91 
per  cent,  sulphuric  acid. 

In  the  box  experiments  the  acid  was  allowed  to 
run  into  the  cyanide  previously  dissolved  in  water. 
In  the  room  experiments  the  water  and  acid  were 
poured  together  in  a  two-gallon  earthen  vessel,  into 
which  the  cyanide  was  dropped.  As  the  potassium 
cyanide  was  on  the  average  of  96.7  per  cent,  purity, 
containing  40.14  per  cent,  hydrocyanic  acid,  it  would 
have  furnished  0.08028  gramme  of  that  acid  per  cubic 
foot  if  all  had  been  liberated.  Professor  Penny  found, 
as  he  expected,  that  a  certain  amount  of  hydrocyanic 
acid  always  remained  in  solution  in  the  generating 
liquid,  depending  on  the  temperature  and  the  time  of 
exposure  of  the  latter.  In  the  case  of  the  box  experi- 
ments this  residual  hydrocyanic  acid  varied  from  2  to 
8  per  cent,  of  the  whole  amount  originally  present,  and 

186 


DIFFUSION   OF   HYDROCYANIC   ACID   VAPOR       187 

after  standing  over  night  it  was  as  little  as  0.66  per 
cent.,  averaging  4.71  per  cent.;  the  particular  amount 
was  determined  for  each  experiment  and  was  deducted 
to  determine  the  amount  of  actually  liberated  or  avail- 
able hydrocyanic  acid  vapor. 

In  the  case  of  the  room  experiments  the  average 
residual  hydrocyanic  acid  was  found  to  be  4.97  per 
cent,  of  the  whole  amount;  this  was  deducted  in  each 
case  to  determine  the  liberated  or  available  vapor. 
Thus,  at  the  temperature  at  which  the  experiments 
were  made,  both  with  large  and  small  quantities  of 
reagents,  the  proportion  of  acid  and  water  used  gave 
about  95  per  cent,  of  available  vapor.  This  liberated 
or  available  vapor  on  an  average  0.07623  gramme  per 
cubic  foot  of  space,  called  by  Professor  Penny  the 
"HCN,"  was  taken  as  the  basis  of  calculation  to 
determine  the  ratio  of  diffusion;  in  other  words,  that 
amount  found  in  a  cubic  foot  would  be  called  a  diffusion 
of  loo  per  cent. 

Quite  as  important  as  the  average  percentage  of 
diffusion,  Professor  Penny  shows,  is  the  average  per- 
centage of  fluctuation.  In  such  work  absolute  uni- 
formity of  conditions  with  the  facilities  available  is 
not  attainable;  hence  repeated  trials  with  conditions 
apparently  the  same  often  give  different  results,  some- 
times widely  different.  As  perfectly  air-tight  walls,  both 
of  boxes  and  of  the  room,  are  difficult  to  secure,  there 
are  varying  conditions  that  make  no  two  trials  exactly 
alike.  Such  discrepancies,  although  they  cannot  be 
foreseen,  may  be  explained  by  variations  in  the  force 
and  direction  of  the  wind,  varying  amounts  of  humidity 
and  the  host  of  minor  conditions  that  are  never  quite 


1 88  FUMIGATION   METHODS 

the  same,  but  yet  influence  the  result.  Hence,  in 
addition  to  the  average  diffusion,  the  fluctuation  in 
percentage  between  repeated  trials  is  given.  This 
indicates  the  degree  of  constancy  in  the  work. 

It  might  be  supposed,  says  the  author,  as  pure 
hydrocyanic  acid  is  a  liquid  that  boils  at  80°  F. ,  and 
inasmuch  as  most  practical  applications  of  the  acid 
are  made  below  that  temperature,  that  ordinarily 
but  a  small  portion  of  the  acid  would  vaporize,  and 
that  this  portion  would  diminish  rapidly  with  a  falling 
temperature.  Such,  however,  is  not  the  case.  The 
proportion  of  the  acid  used  in  Professor  Penny's  experi- 
ments, if  it  were  all  liberated,  would  amount  in  weight 
and  also  in  volume  to  only  one  five-hundredth  part  of 
the  air.  As  the  vapor  pressure  of  the  acid  is  half 
an  atmosphere  at  40°  F. ,  it  is  clear  that  even  in  this 
low  temperature  many  times  as  much  acid  as  could 
ever  be  used  (in  fact,  over  two  hundred  times  as  much) 
would  still  remain  in  the  state  of  vapor.  Hence  the 
condensation  of  the  minute  trace  of  hydrocyanic  acid 
that  is  ever  used  in  practice  would  be  impossible  at  any 
natural  temperature  whatever.  The  "  surf  ace  con- 
densation," referred  to  later  by  Professor  Penny,  is  the 
solution  of  the  acid  in  the  film  of  condensed  moisture 
adherent  to  walls  and  other  surfaces. 

The  results. — The  results  summed  up  below  were 
obtained  by  Professor  Penny  with  a  box  of  sixty  cubic 
feet  capacity,  of  which  the  horizontal  dimensions  were 
8  feet  by  3  feet  and  the  vertical  depth  2^  feet.  The 
box  had  double  wooden  walls,  with  paper  between 
them,  and  made  as  nearly  air-tight  as  possible.  The 
generator  and  the  point  at  which  the  sample  was 


DIFFUSION   OF   HYDROCYANIC   ACID   VAPOR       189 

taken,  or  the  "  intake,"  were  in  one  case  at  the  same 
end  of  the  box,  in  the  other  case  at  opposite  ends. 
The  ' '  diffusion  time ' '  was  the  time  elapsed  between 
the  liberation  of  the  vapor  and  the  taking  of  the 
sample. 

"It  appears,"  says  Professor  Penny,  "from  the 
results  obtained  that  immediately  after  the  generation 
of  the  hydrocyanic  acid,  as  would  be  expected,  there 
is  an  excess  of  it  around  the  generator,  that  this  excess 
disappears  within  two  minutes,  leaving  but  one-third 
the  normal  quantity  at  that  point,  and  that  at  the  oppo- 
site end  there  is  a  still  greater  excess,  viz.,  two  and 
one-half  times  the  normal  amount ;  that  this  latter 
excess  in  turn  rapidly  falls  and  the  vapor  around  the 
generator  again  increases  in  amount,  so  that  there  is  a 
tendency  toward  equilibrium,  though  considerably 
over  twenty  minutes  would  be  required  to  approximate 
perfect  equilibrium.  Hence,  for  the  duration  of  a 
practical  trial  by  far  the  greater  amount  of  vapor 
would  be  in  the  end  of  the  box  farthest  from  the  gen- 
erator. 

' '  The  fluctuations  between  repeated  trials  under 
similar  circumstances  are  relatively  slight ;  that  is, 
uniformity  is  the  rule.  What  is  found  true  in  one 
instance  is,  with  due  regard  to  the  general  character 
of  the  work  which  precludes  extreme  accuracy,  sub- 
stantially true  in  similar  instances.  This  may  be 
attributable  in  part  to  the  double  walled  and  paper- 
lined  box,  which  reduced  the  influence  of  air  currents 
to  a  minimum." 

Diffusion  in  box. — "The  following  results  in  the 
second  experiment  were  obtained  with  a  box  of  29 


190  FUMIGATION   METHODS 

cubic  feet  capacity,  of  which  the  horizontal  dimensions 
were  13^  feet  by  i^  feet  and  the  vertical  i}^  feet. 
The  experiments  covered  five  different  cases,  and  it 
appears  first  that  there  is  less  uniformity  than  with 
the  box  of  60  cubic  feet.  This  may  be  due,  and  prob- 
ably is  in  part,  to  the  structure  of  the  two  boxes,  the 
former  having  rawhide  roofing  paper  sides  and  the 
latter  double  sides  with  paper  lining.  Hence  in  the 
case  of  the  box  under  discussion  outside  disturbing 
influences  may  have  been  felt  to  a  greater  degree. 

' '  With  the  intake  at  the  same  end  of  the  box  as 
the  generator,  after  three  minutes'  diffusion  time  there 
appeared  in  a  single  instance  a  deficit  of  acid  vapor  as 
compared  with  the  normal,  in  two  other  instances  a 
considerable  excess.  The  extreme  fluctuations  found 
show  forcibly  the  inconstancy  of  spontaneous  diffusion, 
especially  with  this  arrangement  and  after  a  short 
interval  of  time.  With  the  generator  at  the  middle  of 
the  box  and  the  intake  at  the  end  there  is  greater  uni- 
formity and  after  ten  minutes  a  considerable  deficit, 
which  deficit  remains  practically  the  same  for  a  half 
hour  ;  the  amount  of  vapor  then  gradually  diminishes, 
doubtless  through  leakage.  It  appears  then  that  of 
these  two  arrangements,  viz.,  the  generator  in  one 
case  at  the  end  of  the  box  and  again  in  the  middle, 
the  latter  gives  more  uniform  results  and  also  a  more 
even  distribution  of  the  acid  vapor.  This  is,  perhaps, 
what  would  be  expected,  but  it  must  be  noted  that 
even  in  the  latter  case  the  quantity  of  vapor  in  one 
instance  is  double  what  it  is  in  two  other  instances. 

"/«  summary,  then,  be  it  noted  of  these  cases  of 
spontaneous  diffusion  that  within  a  half  hour  of  diffu- 


DIFFUSION   OF   HYDROCYANIC  ACID   VAPOR      1 91 

sion  time  the  amount  of  hydrocyanic  acid  vapor  at  a 
given  point  may  be  as  little  as  23  per  cent,  of  the 
normal  and  as  high  as  272  per  cent.,  or,  with  the  same 
quantity  of  reagents  per  cubic  foot  and  in  the  same 
box,  at  one  point  there  may  be  twelve  times  as  much 
acid  vapor  as  at  another.  Of  course  this  inequality 
would  not  continue  long,  but  it  does  exist  in  certain 
cases  for  a  time.  Hence  it  must  be  apparent,  if  we 
rely  on  spontaneous  diffusion,  that  the  amount  of 
cyanide  used  per  cubic  foot  is  no  guarantee  on  the  one 
hand  of  sufficient  acid  vapor  to  do  the  work,  nor,  on 
the  other,  of  too  little  to  injure  plants." 

Mechanical  mixer. — In  these  tests  a  mechanical 
mixer  was  used  in  the  box  of  twenty-nine  cubic  feet 
capacity.  This  device  consisted  of  a  fan  on  a  hori- 
zontal axis  which  passed  through  the  sides  of  the  box 
and  was  turned  by  means  of  a  crank  from  the  outside. 
The  results  showed  a  remarkable  uniformity  for  work 
of  this  general  character,  varying  from  68  per  cent,  to 
74  per  cent,  of  the  normal.  The  average  is  72  per 
cent. ,  and  this  may  be  taken  as  the  true  measure  of 
efficiency  under  these  conditions,  i.e.,  with  a  similar 
size  and  proportion  of  box  and  equal  loss  from  leakage. 
As  about  5  per  cent,  of  the  total  hydrocyanic  acid  re- 
mains in  solution  in  the  generator,  and  of  the  95  per 
cent,  evolved  72  per  cent,  is  uniformly  diffused,  it  would 
follow  that  about  68  per  cent,  of  the  total  hydrocyanic 
acid  gas  originally  present  in  the  cyanide,  or  approxi- 
mately two- thirds,  becomes  efficient  by  uniform  diffu- 
sion throughout  the  box.  Of  the  remaining  32  per 
cent. ,  aside  from  the  5  per  cent,  left  in  the  generator, 
the  balance,  27  per  cent.,  is  to  be  accounted  for  by 


IQ2  FUMIGATION    METHODS 

leakage  and  by  surface  condensation  on  the  walls  of 
the  box,  or  rather  by  solution  in  the  film  of  moisture 
adherent  to  the  walls. 

Effeft  of  moisture  on  foliage. — "Experiments 
were  designed  to  show  the  effect  of  moisture  adherent 
to  foliage.  A  quantity  of  maple  and  cherry  leaves 
were  held  under  a  hydrant,  then  shaken  to  remove  the 
excess  of  water  and  placed  in  the  diffusion  box.  The 
amount  of  adherent  water  was  about  two  and  three- 
quarter  pounds.  In  each  trial  a  fresh  lot  of  leaves 
was  used,  and  a  mechanical  mixer  or  fan  was  used  to 
complete  the  diffusion.  Two  trials  showed  an  average 
of  54  per  cent,  as  compared  with  72  per  cent,  obtained 
without  the  wet  leaves,  or,  with  the  wet  leaves,  just 
three-fourths  as  much  acid  vapor  is  diffused  through 
the  atmosphere  of  the  box  as  without  them.  This  is 
significant  asv indicating  the  effect  of  wet  foliage.  The 
amount  of  acid  vapor  available  for  killing  insects  is 
diminished  and  the  amount  acting  directly  on  the 
plants  is  increased."  Thus  the  necessity  of  having 
plants  either  in  the  nursery  or  orchard  as  dry  as  pos- 
sible. 

Absorbent  effect  of  fresh  earth. — "In  this  experi- 
ment the  bottom  of  the  2g-cubic  foot  box  was  removed 
and  the  box  was  placed  over  fresh  soil;  the  soil  was 
thoroughly  packed  or  tamped  around  the  edges.  The 
surface  soil  thus  exposed  was  i^  x  13^  feet,  or  about 
20  square  feet.  The  mechanical  mixer  was  used,  as 
noted  above.  The  two  trials,  with  closely  concordant 
results,  show  an  average  of  44.5  per  cent,  of  the  normal 
amount  of  acid  vapor  as  compared  with  72  per  cent,  of 


DIFFUSION   OF   HYDROCYANIC   ACID   VAPOR       193 

soil.  Hence,  in  a  box  resting  on  soil,  about  62  per 
cent,  as  much  acid  vapor  is  available  as  in  a  closed 
box.  It  would  seem  necessary,  then,  in  work  of  this 
sort  over  soil  to  use  nearly  twice  as  much  cyanide  and 
other  reagents  as  in  a  closed  box." 

Diffusion  in  large  room. — "  Bxperiments  were  made 
in  a  rectangular  room  of  which  the  horizontal  dimen- 
sions were  20  feet  9  inches  by  19  feet  i  inch,  and  the 
height  10  feet  n  inches,  and  which  included  4,332 
cubic  feet.  The  walls  and  ceiling  were  plastered  and 
the  floor  was  of  boards  ;  there  were  four  windows  and 
three  doors.  The  crevices  were  stopped  as  far  as 
possible,  but  necessarily  the  room  was  far  from  air- 
tight. Samples  of  air  were  taken  simultaneously  from 
three  different  points  within  the  room.  The  position 
of  two  of  these  points  and  also  of  the  generator  was 
changed  several  times  in  order  to  study  the  diffusion 
in  different  places.  The  generator  was  a  glazed  stone- 
ware vessel  8  inches  in  diameter  and  1 5  inches  high. 
The  charge  of  reagents  in  the  case  of  the  room-experi- 
ments was  the  same  per  cubic  foot  as  in  the  case  of  the 
box-experiments,  in  the  former  amounting  to  866.5 
grammes  cyanide,  1,300  c.  c.  of  concentrated  sulfuric 
acid,  and  1,950  c.  c.  of  water.  The  water  was  poured 
into  the  generator,  the  acid  was  then  poured  into  the 
water,  and  immediately  thereafter  the  cyanide,  wrap- 
ped in  paper,  was  dropped  by  means  of  a  string,  into 
the  acid  mixture." 

General  results. — "After  ten  minutes  of  diffusion 
time,  with  the  generator  in  one  corner  on  the  floor,  the 
amount  of  vapor  in  the  center  of  the  room  at  the  ceiling 


194  FUMIGATION   METHODS 

was  'about  normal,  with  a  trifling  excess.  On  the  floor 
by  the  side  of  the  generator  there  was  none  at  all,  or 
only  a  mere  trace.  On  the  floor  diagonally  opposite 
to  the  generator  it  averages,  with  rather  wide  fluctua- 
tions, 73  per  cent,  of  the  normal.  After  20  minutes 
the  center  at  the  ceiling  showed  a  trifling  loss,  the 
point  on  the  floor  next  to  the  generator  showed  27  per 
cent,  of  the  normal,  and  the  point  on  the  floor  in  the 
opposite  corner  showed  94  per  cent.  After  30  minutes 
these  figures  were  not  greatly  changed  for  the  first  and 
the  last,  while  for  the  second  point,  that  next  to  the 
generator,  the  vapor  is  51  per  cent,  of  the  normal, 
nearly  double  its  amount  after  20  minutes.  After  an 
hour  the  diffusion  is  practically  complete,  the  amount 
of  vapor  at  the  three  points  being  52,  44  and  44  per 
cent,  of  the  normal,  while  after  four  hours  and  a  half 
it  is  25,  24  and  21  per  cent.,  respectively. 

* '  It  is  apparent  that  there  is  a  rapid  loss  in  the  total 
amount  of  acid  vapor  from  the  room  as  a  whole.  This 
loss  cannot  be  easily  estimated  until  there  is  practically 
complete  diffusion,  as  the  average  of  the  three  points 
would  not  necessarily,  nor  even  probably,  give  the 
average  for  the  whole  room.  It  would  seem,  then, 
after  one  hour  there  is  a  trifle  less  than  one-half  of  the 
normal  amount  of  acid  vapor  in  the  room,  and  after 
four  and  one-half  hours  a  trifle  less  than  one-quarter. 
The  rate  of  loss  is  probably  greater  through  a  plastered 
wall  than  through  one  of  boards,  and  it  would  doubt- 
less require  a  special  air-tight  construction  of  a  room 
to  reduce  this  rate  very  considerably.  Hence,  the  con- 
stant loss  must  be  borne  in  mind  in  considering  the 
completeness  of  the  diffusion. 


DIFFUSION   OF   HYDROCYANIC   ACID   VAPOR       195 

"It  is  clear  from  the  results  that  the  acid  vapor 
rises  from  the  generator  vertically,  follows  the  ceiling, 
descends  on  the  opposite  side  of  the  room  and  com- 
pletes the  circuit  by  returning  to  the  generator.  Thus 
the  point  immediately  at  the  side  of  the  generator  is 
the  last  to  receive  any  vapor,  while  the  opposite  point 
on  the  floor  quickly  receives  almost  its  normal  amount. 
This  is  what  might  be  expected  from  the  shape  of  the 
generator,  an  open  jar,  15  inches  high  and  8  inches 
in  diameter,  which  has  the  effect  of  projecting  the 
charge  of  vapor  directly  upward;  and,  furthermore, 
while  the  density  of  hydrocyanic  acid  vapor,  a  very 
little  less  than  that  of  air,  is  not  small  enough  to  cause 
it  to  rise  rapidly,  yet  its  expansion  by  the  heat  of  the 
reaction  is  considerable.  Hence  the  tendency  of  the 
acid  vapor  to  ascend  is,  for  several  reasons,  the  natural 
thing  to  expect,  and  to  secure  rapid  diffusion  a  counter- 
acting cause  must  be  set  to  work.  At  the  moment  of 
generation  the  vapor,  or,  rather,  the  accompanying  con- 
densed steam,  may  be  actually  seen  to  take  the  course 
that  has  been  described,  though  naturally  but  for  a 
minute  or  two. 

' '  When  the  generator  is  moved  to  the  center  of  the 
floor,  the  intake  remaining  in  the  same  place,  after  ten 
minutes  there  is  found  75  and  88  per  cent,  in  the  two 
corners  and  123  per  cent,  in  the  center  of  the  ceiling. 
This  is  in  general  agreement  with  what  has  already 
been  noted,  as  in  this  case  the  two  corners  are  arranged 
alike  in  reference  to  the  generator,  and,  as  before,  the 
greater  part  of  the  acid  vapor  is  at  the  ceiling. 

' '  Where  the  generator  is  in  the  corner  of  the  room 
and  the  three  intakes  are  in  a  vertical  line  in  the 


196  FUMIGATION   METHODS 

center  of  the  room,  one*  near  the  ceiling,  one  near  the 
floor,  and  one  midway  between,  after  twenty  minutes 
practically  the  same  amount  of  vapor  on  an  average  is 
found  at  the  ceiling  and  at  the  middle  point,  whereas 
the  space  near  the  floor  shows  about  one-third  as  much 
as  the  other  two. 

"Where  the  generator  is  covered  with  a  box 
that  extends  on  all  sides  to  the  floor,  the  effect  is 
to  throw  the  vapor  down  to  the  floor.  The  results 
show  a  greater  amount  there  than  in  the  preceding 
arrangement.  This  device  is  quite  inadequate  to 
secure  an  even  distribution  of  vapor. 

' '  In  this  test  the  generator  was  placed  two  feet 
from  a  side  wall  at  the  middle  point,  and  provided  with 
a  horizontal  distributing  tube.  The  intakes  were  in  a 
vertical  line  in  the  center  of  the  room.  The  effect  of 
this  simple  arrangement  was  surprising.  After  ten 
minutes  there  was  practically  a  uniform  distribution  of 
acid  vapor,  at  least  in  so  far  as  the  three  points  of 
sampling  may  be  taken  as  typical,  and  they  seem  to  be 
fairly  representative.  After  twenty  minutes  there  was 
found  to  be  but  a  slight  change,  well  within  the  limits 
of  fluctuation  in  work  of  this  sort.  This  simple  device, 
designed  by  Professor  Sanderson,  is  shown  in  Chapter 
XII.  The  acid  vapor  is  distributed  immediately  with 
surprising  uniformity.  Thus  has  been  solved  perfectly 
the  difficulty  of  securing  an  even  and  speedy  diffusion, 
and  that,  too,  in  a  very  simple  and  practicable  way. 

; '  These  results  may  be  taken  as  showing  fairly  well 
how  much  of  the  hydrocyanic  acid  can  be  accounted 
for,  and  that  is  93  per  cent,  of  what  is  actually  evolved, 
or  about  88  per  cent,  of  the  total  amount  contained  in 


DIFFUSION   OF   HYDROCYANIC   ACID   VAPOR       1 97 

the  cyanide.  Thus,  of  the  total  amount  of  hydro- 
cyanic acid  about  5  percent,  remains  in  the  generator, 
88  per  cent,  is  diffused,  and  7  per  cent,  must  be 
charged  to  leakage  or  surface  condensation  on  the 
walls  of  the  room.  In  the  experiments  with  the  box 
it  was  estimated  that  only  68  per  cent,  of  the  total 
hydrocyanic  vapor  is  actually  efficient,  the  remainder 
being  lost  in  the  ways  suggested.  This  greater  loss 
with  the  smaller  box  is  just  what  we  should  expect, 
for  the  relative  amount  of  wall  surface  as  compared 
with  the  cubic  contents  is  much  greater. ' ' 


CHAPTER    XIX 
RECENT  WORK   WITH    HYDROCYANIC    ACID  GAS 

UCCESSFUL  A PPLI CATION  IN  ENGLAND. — The  black 
currant  bud-mite  and  the  mealy  bug  are  among 
the  most  dangerous  and  elusive  enemies  of 
the  greenhouse  and  garden  in  England.  So 
severe  have  been  the  losses  by  the  former  that  the 
currant  industry  is  in  a  critical  state.  One  grower  is 
reported  as  having  said  recently  that  his  crop  had 
fallen  from  £  1,400  a  year  to  practically  nothing  on 
account  of  the  mite.  The  latter  pest  is  found  gener- 
ally in  the  vinery.  The  application  of  sprays  and 
washes  have  not  been  successful  in  keeping  either  pest 
in  check. 

In  a  recent  paper  by  H.  H.  Cousins,  in  the  Jour- 
nal of  the  Agricultural  College,  at  Wye,  Kent  (Vol. 
XXV.),  he  reports  successful  results  where  hydro- 
cyanic acid  gas  was  used.  Speaking  of  his  experi- 
ments, he  says  the  spread  of  the  black  currant  bud-mite 
is  clearly  due  in  the  first  place  to  the  propagation  by 
cuttings  from  infested  stock.  Buds  of  apparently 
normal  dimensions  frequently  contain  a  few  mites 
capable  of  indefinite  increase.  In  the  case  of  the 
Baldwin  currant  it  is  most  difficult  to  find  a  shoot  free 
from  mites,  even  when  the  buds  appear  quite  healthy. 
Diseased  stock  undoubtedly  spreads  the  infection  by 
the  mechanical  distribution  of  the  mites  on  the  clothes 

iq8 


RECENT   WORK   WITH   HYDROCYANIC   ACID   GAS    1 99 

of  the  men  engaged  in  hoeing,  or  through  the  agency 
of  the  wind  or  of  birds. 

Preliminary  experiments  indicate  that  at  least  forty 
minutes'  exposure  to  the  cyanide  fumes  was  necessary 
to  ensure  the  complete  destruction  of  the  mites. 
Shorter  periods  were  apparently  successful  at  a  first 
inspection,  but  a  further  examination  showed  that 
many  individuals  recovered  after  twenty- four  hours. 
Doses  of  cyanide  varying  from  0.05  gramme  to  0.4 
gramme  per  cubic  foot  were  tested.  A  minimum  of 
0.2  gramme  per  cubic  foot  was  satisfactory.  A 
stronger  dose  than  0.3  is  not  desirable. 

Cuttings  and  young  bushes. — About  2,000  diseased 
bushes  intended  for  planting  were  treated  January  3d 
as  follows  :  They  were  tied  in  bundles  and  placed  in  a 
heap  on  the  ground.  Four  hurdles  were  arranged  as 
a  support,  and  the  whole  covered  with  a  waterproof 
cloth.  A  small  vessel  was  placed  on  the  ground  in 
the  center  of  the  heap  of  bushes.  One  htindred  cubic 
centimeters  of  water  (about  4  ounces)  were  added, 
followed  by  an  equal  volume  of  strong  sulphuric  acid. 
Thirty-six  grammes  (about  i^  ounces)  of  commercial 
98  per  cent,  potassium  cyanide  was  wrapped  in  thin 
blotting-paper  and  dropped  cautiously  into  the  vessel 
of  acid  and  water.  The  hand  was  at  once  withdrawn 
and  the  canvas  carefully  pressed  down  all  round  with 
lengths  of  timber.  After  one  hour  the  cloth  was 
removed  and  the  operation  was  complete. 

Mr.  Theobald  conducted  a  systematic  microscopic 
analysis  of  the  treated  buds,  and  established  the  fact 
that  this  treatment  had  destroyed  all  the  mites.  The 
bushes  were  planted  out  in  disease-free  soil  and  were 


20O  FUMIGATION   METHODS 

under  constant  inspection.  A  fortnight  later  a  second 
batch  of  young  bushes  was  similarly  treated  and  with 
identically  good  results. 

The  cost  of  chemicals  is  only  about  a  penny  per 
thousand  bushes  and  the  labor  involved  trifling.  All 
cuttings  should  be  fumigated  before  being  set.  Black 
currants  so  quickly  come  to  a  good  bearing  size  that 
it  would  be  well  to  grub  a  badly  infested  plantation 
and  start  afresh  with  fumigated  young  stock. 

To  the  above  report  A.  D.  Hall,  the  principal  of 
the  college,  adds  the  following:  "I  am  not  by  any 
means  disposed  at  present  to  definitely  recommend  the 
hydrocyanic  process  other  than  by  way  of  experiment, 
and  until  we  have  seen  more  results  I  should  prefer  to 
say  nothing.  If  the  process  recommended  be  carried 
out  in  the  winter,  when  the  temperature  is  low  and 
the  bushes  in  a  dormant  state,  no  injury  whatever  is 
done  to  the  plants.  The  real  difficulty  lies  in  the  eggs 
of  the  mite  ;  it  seems  to  be  always  laying  eggs,  except 
perhaps  in  the  very  coldest  weather ;  and  though  we 
are  now  sure  the  adult  mite  is  killed  by  the  treatment 
we  are  still  doubtful  about  the  eggs.  The  treatment 
of  large  bushes  in  situ  has  failed  on  the  whole." 

Mealy  bug  in  vineries  and  conservatories. — Through 
the  kindness  of  Colonel  Ready,  of  Goudhurst,  and  Mr. 
Hammond,  of  Ramsgate,  Mr.  Cousins  was  enabled  to 
try  the  effect  of  cyanide  fumigation  under  a  variety  of 
conditions.  Three  vineries,  A,  B,  and  C,  were  twice 
treated,  as  was  also  a  large  conservatory.  In  each 
case  the  attack  of  the  mealy  bug  was  severe. 

Vinery  A. — The  capacity  of  this  house  was  3,430 
cubic  feet.  It  contained  an  early  variety  and  was 


RECENT  WORK  WITH   HYDROCYANIC  ACID   GAS   2OI 

treated  when  vines  were  in  full  bloom  with  the  follow- 
ing :  Cyanide,  18  ounces;  acid,  27  fluid  ounces;  i 
quart  of  water.  The  temperature  was  60°  F.  Time 
of  exposure  was  half  an  hour.  The  work  was  done 
after  sunset.  The  mealy  bug  was  destroyed,  foliage 
unhurt,  but  three-quarters  of  the  bloom  was  injured. 
A  few  mealy  bugs  appeared  at  the  close  of  the  season, 
after  the  grapes  had  been  gathered.  A  second  fumi- 
gation was  therefore  decided  upon  and  the  results  were 
satisfactory. 

Vinery  B  had  a  capacity  of  3,825  cubic  feet  and 
contained  a  late  variety.  It  was  treated  before  vines 
bloomed  with  the  following  dose:  Cyanide,  27  ounces; 
acid,  40  ounces;  water,  60  ounces.  The  application 
was  made  after  sunset  and  exposed  three  hours  at  a 
temperature  60°  F.  The  mealy  bug  was  destroyed 
and  there  was  no  injury  to  vines.  A  few  insects  ap- 
peared in  the  autumn  and  a  second  fumigation  was 
given,  with  the  same  success  as  in  the  previous  case. 

Vinery  C  had  a  capacity  of  1,990  cubit  feet  and 
was  planted  with  an  early  variety.  It  was  treated 
when  the  grapes  were  the  size  of  peas  with  the  follow- 
ing chemicals  :  Cyanide,  6  ounces;  acid,  9  ounces; 
water,  15  ounces.  The  temperature  was  65°  F. ; 
weather  very  sultry  at  the  time.  Time  of  exposure 
was  forty  minutes  and  application  was  made  at  3 
P.M.  The  grapes  were  browned  and  killed,  while  the 
foliage  was  uninjured.  The  mealy  bug  was  de- 
stroyed. The  vinery  was  kept  on  the  cool  side,  plenty 
of  air  given,  and  splendid  growth  and  promise  of  fruit 
for  next  year  was  obtained.  A  few  mealy  bugs  ap- 
peared in  October.  Fumigation  was  repeated.  All 


202  FUMIGATION    METHODS 

the  bugs  were  destroyed.  The  season  had  so  far  ad- 
vanced, however,  that  the  eggs  were  to  be  found  on  the 
shoots.  Painting  the  rods  with  the  winter  alkali  wash 
in  the  spring  and  a  fumigation  before  the  bloom 
appears  to  have  been  decided  upon. 

A  conservatory  of  300  cubic  feet,  containing  mixed 
flowers  and  ornamental  plants  and  ferns,  etc. ,  infested 
with  aphis  and  mealy  bug  was  fumigated  after  sunset 
with  cyanide,  8  ounces;  acid,  12  ounces;  water,  20 
ounces.  The  temperature  was  50°  F.  Time  of  ex- 
posure was  three-quarters  of  an  hour,  with  complete 
success.  There  was  no  injury  to  maidenhair  fern 
or  any  of  the  plants  under  treatment.  The  cost  did 
not  exceed  i  shilling. 

A  greenhouse  of  2,000  cubic  feet,  containing  chrys- 
anthemums in  full  bloom  severely  infested  with  green- 
fly, was  treated  one  hour  before  sunset  with  cyanide, 
3^  ounces  (0.05  gramme  per  cubic  foot)  ;  acid,  5 
ounces  ;  water,  9  ounces.  The  temperature  was  52° 
F.  and  the  time  of  exposure  was  25  minutes.  Every 
aphis  was  killed,  also  slugs,  flies,  wasps  and  butter- 
flies. A  toad  was  uninjured.  Not  a  petal  or  leaf  was 
hurt. 

Conclusions. — Mr.  Cousins  is  of  the  opinion  that 
these  experiments  should  encourage  practical  men  to 
give  cyanide  fumigation  a  thorough  trial  for  such 
pests  as  are  beyond  ordinary  treatment.  For  green- 
house work  he  recommends  the  following  :  If  the 
house  be  under  10,000  cubic  feet  one  vessel  will  suffice; 
if  over,  provide  a  vessel  for  each  10,000  cubic  feet. 
Arrange  the  ventilators  so  that  they  can  be  opened 


RECENT  WORK   WITH   HYDROCYANIC   ACID   GAS   203 

from  without.  The  foliage  of  the  plants  should  be 
dry.  A  temperature  not  exceeding  60°  F.  and  prefer- 
ably of  50°  F.  is  desirable.  Above  60°  F.  there  is 
risk  of  injury  to  the  foliage. 

For  mealy  bug,  3  ounces  cyanide,  5  ounces  acid, 
15  ounces  water  per  1,000  cubic  feet,  either  before  the 
vines  bloom,  or  when  grapes  are  coloring,  or  after  the 
crop  has  been  gathered.  At  either  of  these  stages  no 
harm  results  to  either  foliage  or  fruit.  Avoid  fumi- 
gation when  the  vines  are  in  bloom,  or  before  the 
grapes  have  commenced  to  ripen. 

For  ordinary  greenhouse  pests,  such  as  aphis, 
dolphin,  whitefly,  slugs,  woodlice,  red-spider,  and 
caterpillars,  a  dose  not  exceeding  1 24  to  2  ounces  cya- 
nide, 4  ounces  acid,  7  ounces  water  per  1,000  cubic 
feet,  has  been  found  satisfactory  in  England.  For  a 
detailed, account  of  greenhouse  fumigation  see  Chap- 
ter XIV. 

Use  in  New  South  Wales. — In  the  center  of  the 
citrus-growing  belt  of  New  South  Wales,  W.  J.  Allen, 
an  expert  of  the  government,  has  conducted  some  very 
satisfactory  experiments  with  hydrocyanic  acid  gas  in 
cooperation  with  the  Glenorie  Progress  Association. 
Various  sprays  were  tried  at  the  same  time  and  com- 
pared with  the  gas  treatment.  In  his  report  of  the 
practical  tests,  printed  in  Vol.  XII.  of  the  Agri- 
cultural Gazette  of  New  South  Wales  (see  also  Agri- 
cultural Gazette  for  August,  1899,  an^  July,  1900),  Mr. 
Allen  says: 

The  fumigation  of  the  trees  with  hydrocyanic  acid 
gas  gave  the  best  results  of  all.  This  was  conceded 


2O4 


FUMIGATION   METHODS 


by  all  growers  who  Allowed  up  the  experiments. 
The  cost  of  treatment  was  the  same  as  that  of  the  blue 
oil  emulsion  and  slightly  in  excess  of  the  resin  work. 


1 


FIG.    75 — FUMIGATING    IN    G.    TURNER  S    ORCHARD    AT 
GLENORIE,    NEW   SOUTH   WALES.      (AFTER   ALLEN) 

The  fumigated  trees  made  a  better  growth  than  those 
in  the  same  orchard  not  treated. 

Several  prominent  growers  requested  Mr.  Allen  to 
fumigate  one  or  two  badly  infested  trees  in  their 
orchards,  and,  by  the  way  of  experiment,  wished  him 
to  give  the  trees  an  extra  charge.  They  wanted  to 
make  sure  of  killing  the  scale  and  see  also  the  effect  on 


206  FUMIGATION   METHODS 

the  tree.  The  trees  were  treated  in  the  hottest  part  of 
the  day.  This,  added  to  the  overcharge  of  cyanide, 
caused  many  of  the  leaves  to  fall;  yet  it  had  little  or 
no  effect  on  the  fruit,  and  all  the  scales  were  killed, 
Two-thirds  of  the  dose  would  have  been  quite  sufficient 
to  have  cleaned  the  trees. 

L,emons  and  mandarins  stand  the  fumigation  much 
better  than  the  orange.  Taking  two  trees  of  equal 
size  and  treating  them  with  the  same  charge,  while 
the  mandarin  would  not  show  any  ill  effect,  the  orange 
tree  would  lose  a  few  of  its  leaves.  Mr.  Allen,  there- 
fore, recommends  always  treating  the  latter  at  night 
or  on  cool  and  dull  days.  The  night  treatment  appears 
to  be  the  best,  as  a  charge  which  would  in  the  day- 
time remove  leaves,  and,  perhaps,  burn  the  tender 
parts  of  the  twigs,  would  have  no  detrimental  effect 
where  the  work  was  performed  at  night.  He  thinks 
that  lemons  and  mandarins  can  be  treated  with  very 
good  results  during  the  daytime,  except  on  very  hot 
days. 

When  Mr.  Allen  first  commenced  his  fumigating 
experiments  in  New  South  Wales  the  price  of  tents 
was  so  high  as  to  make  it  appear  to  growers  that  this 
method  of  treating  trees  was  quite  out  of  the  reach  of 
the  average  fruit-grower ;  but  several  large  growers, 
rather  than  pay  a  high  price  for  material,  bought 
strong  calico  and  sail-cloth,  and  made  tents  from  these 
materials,  and  these,  after  a  fair  trial,  have  stood  the 
test  quite  as  well  as  the  more  expensive  duck  tents, 
and  cost  only  about  one-quarter  as  much. 

The  cost  of  material  for  tents  made  of  sail-cloth  6 
feet  wide,  estimated  by  Mr.  Allen,  is  as  follows  for  the 


FIG.   77 — AVERAGE    SPECIMEN    OF    FRUIT    FROM    A    FUMIGATED 
TREE    IN    NEW    SOUTH    WALES    ORCHARD.       (AFTER   ALLEN) 


FIG.  78 — AVERAGE  SPECIMEN  OF  FRUIT  FROM  A  TREE  IN 

SAME  ORCHARD  AS  ABOVE,  NOT  FUMIGATED 

(AFTER  ALLEN) 


20%  FUMIGATION   METHODS 

different  sizes  :  Tents  1^5  feet  high,  24  feet  in  circum- 
ference, require  16  yards  of  sail-cloth  6  feet  wide, 
which,  at  is.  3^.  per  yard,  will  cost  £i\  tents  18  feet 
high,  36  feet  in  circumference,  require  30  yards  of  sail- 
cloth 6  feet  wide,  which,  at  is.  $d.  per  yard,  will  cost 
£i  ijs.  6d. 

He  says  these  are  two  of  the  most  useful  large- 
sized  tents  for  general  use.  The  former  is  quite  large 
enough  to  cover  trees  10  feet  high  and  8  feet  in  diam- 
eter, while  the  latter  is  large  enough  to  cover  trees  1 3 
feet  high  and  10  to  12  feet  in  diameter.  If  larger  trees 
are  to  be  fumigated  it  is  best  to  have  octagonal  sheets, 
sizes  either  41  x  41  or  50  x  50.  A  sheet  is  always 
much  easier  to  put  over  the  tree  than  a  tent  where 
large  trees  are  being  handled.  The  price  of  making 
the  tents  is  not  given,  as  any  person  having  a  sewing- 
machine  can  sew  them  together.  To  make  the  former 
tent  the  material  is  cut  in  two.  Find  the  center  of 
each  length,  and  from  this  point  measure  back  3  feet 
on  opposite  sides,  draw  a  line  diagonally  across  from 
one  point  to  the  other,  and  cut  as  marked.  After  cut- 
ting the  two  pieces  can  be  sewn  together.  For  the 
large-sized  tent,  the  30  yards  must  be  cut  in  three 
pieces  of  10  yards  each,  which  should  be  cut  again  in 
an  exactly  similar  manner  to  the  smaller-sized  tent 
and  sewn  together.  Great  care  must  always  be  taken 
to  keep  the  tents  perfectly  air-tight. 

Good  results. — The  outcome  was  very  gratifying, 
and  Mr.  Allen  says  :  ' '  I  feel  quite  safe  in  saying  that 
by  the  autumn  of  1901  there  will  be  over  a  thousand 
tents  in  use  in  New  South  Wales,  with  the  result  that 
there  will  be  more  clean  and  better  fruit  for  export 


RECENT   WORK    WITH   HYDROCYANIC   ACID   GAS    2OQ 


and  home  consumption,  and  more  healthy  and  vigor- 
ous trees  found  in  our  fruit-growing  districts.  In 
most  cases  the  fumigation  was  successful  wherever 
experiments  were  conducted,  and  there  can  be  no  bet- 
ter proof  than  that  the  growers  are  adopting  this 
method  of  destroying  scales  more  and  more  as  they 
become  acquainted  with  its  advantages.  '  ' 

Various  materials  have  been  used  for  making  tents. 
Mr.  Allen  thinks  that  tents  made  of  sail-cloth  will  be 
found  durable  and  economical.  We  reproduce  here- 
with the  table,  compiled  by  Mr.  Allen,  for  the  various 
amounts  of  chemicals  to  be  used  in  orchards  in  New 
South  Wales. 

FUMIGATION  TABLE   FOR  NEW   SOUTH  WAI.ES 
ORCHARDS 


43 
54 
65 
85 
101 
118 
146 
170 
195 
232 
265 
298 


432 
437 
492 
547 
601 
540 
608 
675 
743 
810 


735 

817 


1,062  9 
1,144 

778 

875 

972 

1,069 

1,168 

1,264 

1,361 

1,458 

947 


1,141 
1,255 
1,369 
1,481 
1,597 
1,711 
1,050 


15 


2IO 


FUMIGATION    METHODS 


AXA82T8   FUMIGATION  TABLE   FOR   NEW   SOUTH   WAIVES 
ORCHARDS  —Continued 


L 

v 

1 

^ 

W 

1 

•1 

$ 

| 

j. 

f 

3 

C 

t 

Q 

!§i 

* 

Q 

^ 

3 

5 

fee 

<L 

8 

^ 

**2 

2 

5 

a 

* 

^ 

jjj 

s 

| 

to 

^ 

oz. 

oz. 

02". 

OZ. 

oz. 

oz. 

14 

9 

,191 

6 

6 

18 

18 

17 

3,718 

18J4 

55 

14 

10 

,323 

61^ 

19 

18 

18 

3,937 

19/4 

19)4 

58 

14 

11 

,455 

7)4 

7)4 

21 

18 

19 

4,156 

2014 

20J4 

61 

14 

12 

,587 

7% 

7% 

22 

18 

20 

4,374 

21% 

21% 

C5 

14 

13 

,720 

8)4 

8J^ 

24 

18 

21 

4,593 

22% 

22%. 

68 

14 

14 

,852 

9)4 

9)4 

27 

18 

22 

4,812 

24 

24 

72 

14 

15 

,984 

9^4 

9% 

28 

18 

23 

5,030 

25 

25 

75 

14 

16 

2,116 

io)4 

30 

18 

24 

5,249 

26 

26 

78 

15 

8 

1,215 

6 

6 

18 

19 

13 

3,168 

46 

15 

9 

1.367 

6% 

654 

19 

19 

14 

3,412 

17 

17 

51 

15 

10 

1.519 

7)4 

7^6 

22 

19 

15 

3,656 

18 

18 

54 

15 
15 

11 
12 

1,671 
1,823 

9 

8M 

24 
27 

19 
19 

16 

17 

3,899 
4,143 

20U 

57 
60 

15 

13 

1,975 

9% 

9% 

27 

19 

18 

4,387 

21  8 

%\y> 

64 

15 

14 

2,127 

10J4 

31 

19 

19 

4,630 

23 

23 

69 

15 

15 

2,279 

ii)4 

11)4 

33 

19 

20 

4,874 

24 

24 

72 

15 

16 

2,430 

12 

12 

36 

19 

21 

5,118 

25 

25 

75 

15 

17 

2,582 

12^4 

12% 

37 

19 

22 

5,362 

26J4 

26J4 

78 

15 

18 

2,734 

13J^ 

13)4 

40 

19 

23 

5,605 

28 

28 

84 

15 

19 

2,886 

14^4 

14^4 

42 

19 

24 

5,849 

29 

29 

87 

15 

20 

3,038 

15 

15 

45 

20 

13 

3,512 

17^ 

52 

16 

10 

1,728 

8}^ 

24 

20 

14 

3,782 

18J4 

18)4 

55 

16 

11 

1,901 

9J/2 

9)4 

28 

20 

15 

4,053 

20 

20 

60 

16 

12 

2.074 

10*4 

10)4 

30 

20 

16 

4,323 

63 

16 

13 

2,247 

11 

11 

33 

20 

17 

4.593 

22% 

22% 

67 

16 

14 

2,420 

12 

12 

36 

20 

18 

4,863 

24 

24 

72 

16 
16 

15 
16 

2,492 
2,765 

18% 

13% 

37 
40 

20 
20 

19 
20 

5,133 
5,404 

^ 

25)4 
27 

75 

81 

16 

17 

2,938 

14J4 

43 

20 

21 

5,674 

28 

28 

84 

16 

18 

3,111 

15)4 

i§y> 

46 

20 

22 

5,944 

29^ 

29)4 

88 

16 

19 

3,284 

16)4 

16J4 

48 

20 

23 

6,214 

31 

31 

93 

16 

20 

3,456 

17J4 

1714 

51 

20 

24 

6,484 

32 

32 

96 

16 

21 

3,629 

18 

18 

54 

21 

14 

4,168 

20J4 

60 

16 

22 

3,802 

19 

19 

57 

21 

15 

4,466 

22 

22 

66 

17 

12 

2,341 

11*4 

H)4 

34 

21 

16 

4,763 

23)4 

69 

17 

13 

2,536 

12}^ 

12)4 

37 

21 

17 

5,061 

25  2 

25 

75 

17 

14 

2,731 

13}4 

13J4 

40 

21 

18 

5,359 

26J4 

26)4 

78 

17 

15 

2,926 

14J4 

14)4 

43 

21 

19 

5,657 

28 

28 

84 

17 

16 

3,122 

151^ 

15/4 

46 

21 

20 

5,954 

29^ 

29)4 

88 

17 

17 

3,317 

16^ 

16V«j 

49 

21 

21 

6,252 

31 

31 

93 

17 

18 

3,512 

17)4 

17)4 

52 

21 

22 

6,550 

32J4 

32)4 

97 

17 

19 

3,707 

18)4 

18)4 

55 

21 

23 

6,847 

34 

34 

102 

17 

20 

3,901 

19/4 

58 

21 

24 

7,145 

3514 

35)4 

106 

17 

21 

4.096 

20j| 

20  J4 

60 

21 

25 

7,443 

37 

37 

111 

17 

22 

4,291 

21)4 

21  J4 

63 

22 

15 

4.901 

24J4 

24)4 

73 

18 

12 

2,625 

13 

13 

39 

22 

16 

5,228 

26 

26 

78 

18 

13 

2,843 

14 

14 

42 

22 

17 

5,555 

27^ 

27)^ 

82 

18 

14 

3,062 

15^4 

1514 

45 

22 

18 

5,881 

29 

29 

87 

18 

15 

3,281 

16/4 

16J4 

48 

22 

19 

6,208 

31 

31 

93 

18 

16 

3,500 

™ 

17% 

52 

22 

20 

6,535 

32J4 

32)4 

97 

RECENT   WORK   WITH   HYDROCYANIC   ACID   GAS   211 


AI^EN'S   FUMIGATION   TABLE   FOR  NEW  SOUTH   WAIVES 
ORCHARDS.— Continued 


23 


7,188 
7,515 
7,842 
8,168 
8,495 
5,357 
5,714 
6,071 


oz. 
34 


40^ 
42 


oz. 
34 


8* 


30 


oz. 
102 
106 
112 
117 
121 
126 
79 
85 
90 


6.785 
7,142 
7,500 

7,857 
8,214 
8,571 


oz. 
32 


86 


41 
4214 


41 


oz. 

96 
100 
106 
112 
117 
123 
127 
133 
138 


As  a  final  caution,  Mr.  Allen  says  the  full  height 
and  width  of  the  tree  should  be  taken  after  the  tent  is 
in  place.  Give  a  full  charge  of  chemicals;  it  is  better 
to  give  a  fraction  of  an  ounce  too  much  than  too  little. 
Especial  attention  is  called  to  Fig.  76,  reproduced  from 
Mr.  Allen's  report.  For  full  directions  for  making 
and  applying  the  gas,  see  Chapters  II.  and  V.  to  X., 
inclusive. 

Orchard  work  in  Cape  Colony,  South  Africa. — The 
fumigation  of  orchards  in  Cape  Colony  is  largely  due 
to  the  work  of  Prof.  Charles  P.  Lounsbury,  the  Gov- 
ernment Entomologist.  The  methods  followed  are 
very  similar  to  those  used  in  California.  The  condi- 
tions, however,  governing  the  citrus  industry  of 
southern  California  are  somewhat  different  from 
those  found  in  Cape  Colony.  In  California  the  black 
scale  is  one  of  the  principal  pests  against  which  fumi- 
gation is  conducted.  This  insect  is  practically  un- 
known to  the  colonial  fruit  growers,  and  where  it  does 
exist  it  is  kept  in  check  by  natural  enemies.  In  point 


212  FUMIGATION   METHODS 

of  prominence,  the  red»scale  ranks  next  to  the  black 
scale  in  California.  The  red  scale  is  also  familiar  to 
fruit  growers  in  the  colonial  orchards.  Considering  all 
things,  Professor  Lounsbury  is  of  the  opinion  that 
fumigation  conducted  by  the  contract  system  would 
be  more  advantageous  to  the  colony  than  that  done  by 
local  organizations.  There  are  only  a  few  slight  dif- 
ferences in  the  methods  of  operating  and  handling 
sheet  tents.  The  derrick-poles  used  in  the  colonial 
orchards  for  manipulating  the  tents  are  very  much  the 
same  as  those  employed  in  California.  The  dome- 
shaped  covers,  known  as  bell  tents,  are  used. 

In  a  recent  circular  Professor  Lounsbury  makes  the 
following  statement :  ' '  Californians  have  demonstrated 
that  they  can  grow  citrus  fruits  at  a  profit,  in  spite  of 
the  heavy  expense  of  fumigation.  They  fully  realize 
that  they  may  have  to  keep  fumigating  for  an  in- 
definite time.  Their  hope  is,  as  ours,  that  efficient 
natural  enemies  of  the  scale  insects  will  be  found  in 
the  future.  For  South  African  fumigators  it  is  espe- 
cially recommended  that  changing  poles  be  adopted  for 
small  sheets.  A  few  colonial  parties  have  fumigated 
for  the  white  peach  scale,  Diaspis  amygdali,  and  con- 
sider the  remedy  economical  and  satisfactory.  If  light 
weight  sheets,  handled  with  changing  poles,  were 
used  it  is  probable  that  the  gas  treatment  for  this  scale 
would  become  popular  with  a  large  number  of  our 
fruit  growers. ' ' 

New  experiments  at  New  York  Agricultural  Exper- 
iment Station. — Some  timely  and  practical  work  has 
been  recently  completed  at  the  New  York  Agricultural 
Experiment  Station  by  Prof.  V.  H.  Lowe,  the  entomol- 


RECKNT   WORK   WITH    HYDROCYANIC   ACID   GAS   213 


ogist.  Through  the  courtesy  of  Director  W.  H.  Jor- 
dan, the  writer  secured  the  following  summary  of  the 
experiments. 

In  regard  to  these  tests,  Professor  Lowe  says : 
' '  Our  work  consisted  principally  of  experiments  in  the 
orchard  and  with  bud-sticks.  The  former  were  mainly 
for  the  purpose  of  determining  the  strength  of  gas  re- 
quired to  kill  the  scale  during  the  winter  and  spring, 
and  incidentally  the  effect  of  the  gas  upon  the  trees, 
and  the  latter  to  determine  the  effect  of  the  gas  at  dif- 
ferent strengths  upon  fruit  buds.  The  experiments 
in  the  orchard  were  divided  into  two  series,  as  shown 
by  the  following  summaries  : 

WINTER  TREATMENT 

Trees  fumigated  December  13-24;  weather  cloudy 


TREES 

Strength 
of  gas 

Time  of 
exposure 

Results 

6  pli 

8 

8 

7 
7 

,„ 

1 
1 

im 
ach 

0.18  gran 
0.18 
0.25 
0.25 
0.30 
0.30 
0.18 
0.18 
0.30 
0.30 

ime 

Hho 

M 

1 

Yl 
M 

ur 

Scales  not  killed;  trees  uninjured 
Many  live  scales  found;  trees  uninjured 

Scales  dead;  trees  uninjured 

Scales  not  killed;  trees  uninjured 
Tree  dead 

Trees  f-u 


SPRING  EXPERIMENT 

igatedjune  6-8  and  June  16-24;  weather  cloudy 


TREES 

Strength 
of  gas 

Time  of 
exposure 

Results 

4  plum 

0.18  gramme 

J^3  hour 

Scales  dead;  trees  uninjured 

0.18         ' 

^ 

i 

44                       *4                       44                                It 

87 

025 

ri 

• 

Scales  dead  ;    trees  uninjured,    except 

three  trees,  which  showed  slight  in- 

I 

025 

, 

i 

jury  to  foliage 
Scales  dead;  foliage  slightly  injured 

2 

0.30         ' 

M 

1 

Foliage  slightly  injured 

2 

0.30 

i 

214  FUMIGATION   METHODS 

' '  From  this  summary  it  will  be  noticed  that  the  gas 
at  o.i  8  and  0.25  gramme  had  little  or  no  effect  upon 
the  scale  when  the  fumigating  was  done  in  the 
winter;  but  that  0.30  gramme  was  strong  enough  to 
kill  the  scales.  Also  that  the  spring  treatment  resulted 
in  killing  the  scales  with  the  gas  at  o.  18  gramme  and 
only  one-half  hour  exposure.  All  of  the  plum  trees 
treated  were  European  varieties,  and  both  plums  and 
peaches  were  healthy,  vigorous  trees.  We  used  the 
box  fumigator  shown  at  Figs.  43  and  81  in  all  cases. 
Fig.  8 1  shows  our  improved  method  of  fastening  the 
door  on  our  fumigator. 

' '  All  of  the  trees  were  badly  infested  with  the 
scale.  Where  the  term  '  scales  dead '  is  used  it 
means  that  after  very  careful  search  at  various  times 
during  the  summer  following  the  experiment  no  live 
scales  could  be  found.  The  statement  that  the  trees 
were  uninjured  means  that  there  was  no  effect  on  the 
foliage  and  fruit  buds. 

"  The  buds  included  in  the  fumigation  experiment 
were  of  the  following  varieties  :  Apples — Jonathan, 
Fall  Pippin,  Oldenburg,  Ben  Davis,  Fameuse,  and 
Transcendant.  Cherries — May  Duke,  Windsor,  and 
Early  Richmond.  Pears — Anjou,  Bartlett,  Seckel,  and 
Kieffer.  Peaches — Elberta,  Early  Crawford,  Blenheim, 
Early  Rivers,  Beersmock,  and  Alexander.  Plums — 
Italian  Prune,  Reine  Claude,  Bradshaw,  Shropshire 
Damson,  Burbank,  Yellow  Spanish,  Yellow  Egg,  Lom- 
bard, and  De  Soto. 

' '  The  buds  were  fumigated  in  a  small  box  made 
especially  for  the  purpose.  The  gas  was  used  at  the 
following  strengths:  o.  18,  0.22,  and  0.30  gramme. 


FIG.  79 — IMPROVED    METHOD    OF   FASTENING    THE   DOOR 
OF   THE   LOWE   BOX    FUMIGATOR 


2l6  FUMIGATION   METHODS 

The  exposure  in  each  case  was  one -half  hour  and  one 
hour.  The  bud  sticks  were  divided  into  lots,  so  that 
each  variety  received  the  maximum  and  minimum  ex- 
posures of  the  various  strengths  of  gas.  Our  bulletin 
contains  a  number  of  tables  showing  the  percentage  in 
each  case  of  the  buds  that  set,  and  comparisons  are 
made  with  checks. 

"  In  all,  4,483  buds  wrere  treated,  of  which  78  per 
cent.  set.  The  checks  numbered  4,864  buds,  85.5  per 
cent,  of  which  set,  making  a  difference  of  7.5  per  cent. 
in  favor  of  the  checks.  A  careful  examination  of  the 
tables  shows  that  the  gas  evidently  had  no  effect  upon 
any  of  the  varieties  except  peaches,  which  were  slightly 
injured  by  the  0.30  gramme  with  an  exposure  of  one- 
half  hour  and  one  hour.  In  all  cases  the  growth  of  the 
treated  buds  was  nearly  or  quite  equal  to  that  of  the 
checks.  The  conditions  of  the  treated  buds  were  not 
quite  as  favorable,  after  they  had  been  set  into  the 
nursery  trees,  as  those  of  the  checks.  The  treated 
buds  were  set  a  little  out  of  season,  somewhat  later 
than  the  checks.  They  were  also  placed  about  four 
inches  above  the  checks,  where  they  were  too  high  to 
be  protected  by  the  earth  thrown  against  the  trees 
during  the  fall  cultivation.  They  were  also  placed  on 
the  furrow  side  of  the  trees,  thus  endangering  them  to 
injury  during  cultivation.  These  unfavorable  con- 
ditions were  probably,  in  large  part,  the  cause  for  the 
failure  of  the  treated  buds  to  set  equally  as  well  as  the 
checks." 

Sirrine* s  folding  fumigator. — Another  type  of 
fumigator  has  been  developed  and  used  by  Prof.  F.  A. 
Sirrine,  of  the  New  York  Agricultural  Experiment 


RECENT    WORK    WITH    HYDROCYANIC   ACID    GAS    2IJ 

Station.  This  fumigator  is  about  n^  feet  high  and 
S)4  feet  in  diameter.  As  shown  in  Fig.  82,  it  is  six- 
sided  and  is  intended  to  fold  up  when  not  in  use. 


FIG.  8O — THE   SIRRINE   TYPE    OF    FOLDING    FUMIGATOR 

Kach  of  the  six  sides  is  rectangular  and  rigid.  They 
are  fastened  together  by  hinges.  When  in  use  the 
whole  fumigator  is  made  rigid  by  a  series  of  cross- 
braces.  The  top  is  held  in  place  by  a  series  of  hooks. 


2l8  FUMIGATION   METHODS 

The  front  of  the  fumigator  can  be  opened  as  a  double 
door  of  a  width  equal  to  the  shortest  diameter  of  the 
box.  Unbleached  sheeting  so  treated  as  to  be  gas- 
tight  is  used  as  a  cover.  Careful  tests  with  this  fumi- 
gator  showed  that  it  was  practically  gas-tight. 

Fumigation  of  orchard  trees  near  Albany. — A  series 
of  tests  were  made  by  Dr.  E.  P.  Felt,  State  Kntomol- 
ogist,  in  the  spring  of  1900,  with  hydrocyanic  acid  gas 
for  the  purpose  of  ascertaining  its  efficiency  and  prac- 
ticability in  the  latitude  of  Albany,  N.  Y.  A  canvas 
tent  6x6x8  feet  with  a  fixed  pyramidal  hood  7  feet 
high,  as  shown  in  Fig.  81,  was  constructed  of  eight- 
ounce  duck  thoroughly  oiled  with  boiled  linseed  oil. 
The  rectangular  part  of  the  tent  was  supported  on  a 
light  wooden  frame,  to  reduce  the  variation  in  cubic 
contents  as  much  as  practicable.  The  tent  was  lifted 
with  a  thirty-foot  pole  and  eight-foot  gaff,  and  thus 
dropped  over  the  tree.  The  hood  was  kept  extended 
during  the  process  of  fumigation,  as  shown  in  the  fig- 
ure, illustrating  also  the  manner  of  guying  the  pole 
and  tent.  The  tent  and  apparatus  for  handling  it  cost 
about  $38,  but  they  could  undoubtedly  be  made  for  less 
when  several  were  needed.  A  good  pole  and  gaff  from 
near-by  woods  could  be  gotten  at  little  expense.  The 
bottom  of  the  tent  was  provided  with  what  Dr.  Felt 
calls  a  "  sod  cloth."  It  consists  of  a  flap  six  to  eight 
inches  wide,  which  was  covered  with  earth  to  prevent 
the  escape  of  the  gas.  An  uncovered  space  was  always 
left  on  the  windward  side  for  the  insertion  of  the 
chemicals.  The  trees  in  these  tests  were  exposed  to 
the  gas  for  35  minutes.  After  fumigation  the  guy- 
lines  were  released,  the  sod  cloth  uncovered,  and  the 


FIG.  8l — FELT   TYPE    OF   CANVAS    TENT   WITH    PYRAMIDAL 
HOOD 


220  FUMIGATION   METHODS 

tent  quickly  raised  and  dropped  over  an  adjacent  tree. 
It  is  quite  important  to  have  the  pole  on  the  windward 
side  of  the  tent. 

The  trees  were  fumigated  April  19,  20  and  21, 
using  one  ounce  of  potassium  cyanide  to  75,  100  and  150 
cubic  feet  of  space  respectively.  The  trees  fumigated 
were  peach  and  pear,  several  varieties,  and  the  buds 
were  beginning  to  swell.  The  outcome  of  the  tests 
showed  clearly  that  the  scale  was  all  killed,  even  on 
trees  where  the  gas  was  used  at  the  rate  of  one  ounce 
of  cyanide  per  150  cubic  feet  of  space  enclosed. 


A 


CHAPTER   XX 
ECONOMIC  VALUE   OF   FUMIGATION 

FTER  a  most  careful  consideration  of  the  sub- 
ject of  fumigation  with  hydrocyanic  acid  gas 
from  every  point  of  view,  the  writer  is  of  the 
opinion  that  it  is  indispensable  in  orchards, 
nurseries,  greenhouses,  mills,  elevators,  and  various 
other  enclosures  where  insect  pests  are  to  be  destroyed. 
Nothing  is  more  easily  applied,  and  certainly  no  other 
material  has  been  found  so  deadly  to  animal  life.  Its 
cheapness,  quick  diffusion,  and  thoroughness  make  it 
a  practical  remedy  for  ready  use  in  many  ways.  In 
addition  to  the  many  methods  cited,  it  can  be  used  to 
good  advantage  for  the  destruction  of  animals,  such  as 
dogs,  cats,  etc.,  rounded  up  and  captured  in  large 
cities.  Such  animals,  including  old  or  injured  horses 
and  cattle,  could  be  easily  and  painlessly  put  to  death 
by  being  enclosed  in  a  room  in  which  this  gas  could 
be  generated. 

It  is  not  beyond  human  possibility  that  it  may 
supersede  the  primitive  method  of  hanging  and  the 
more  modern  idea  of  electrocuting  criminals.  Cells  or 
death  chambers  could  be  made  in  any  enclosure  in 
which  hydrocyanic  acid  gas  could  be  easily  generated, 
and  the  occupant  painlessly  and  instantly  put  to  death, 
without  any  of  the  horrors  accompanying  the  gallows 
and  electric  chair.  From  the  humanitarian  point  of 
view  it  certainly  deserves  consideration. 

221 


222  FUMIGATION   METHODS 

The  following  letteis  or  quotations  from  scientific 
and  practical  men  who  have  either  used  hydrocyanic 
acid  gas  or  are  thoroughly  familiar  with  its  properties 
and  economic  values  are  interesting  in  this  connection. 
We  have  alluded  to  the  early  history  of  the  discovery 


FIG.   82 — FUMIGATED    CITRUS 

Orchard  of  J.  W.  Henderson,  near  National  City,  California,  only  a 
short  distance  from  the  Stearns  ranch,  on  which  Fig.  83  was 
taken.  Orchards  about  the  same  time.  Note  the  difference. 


of  the  gas  as  an  insecticide  in  Chapter  I.  There  seems 
to  be  some  misunderstanding  as  to  its  first  application 
to  nursery  stock.  In  the  "Year-Book  of  the  United 
States  Department  of  Agriculture  for  1899,"  Dr.  L,.  O. 
Howard,  Entomologist,  is  of  the  opinion  that  he  first 
recommended  the  use  of  hydrocyanic  acid  gas  as  a  dis- 


ECONOMIC   VALUE   OF   FUMIGATION 


223 


infectant  for  nursery  stock.  The  writer  being  aware 
of  the  use  of  this  gas  in  California  upon  nursery  stock 
as  early  as  1890,  wrote  Alexander  Craw,  State  Ento- 
mologist and  Quarantine  Officer  of  California,  who  re- 
plies as  follows : 

First  use  upon   nursery  stock. — "Fumigation    by 


FIG.   83 — SPRAYED     ORANGE   TREE 

Orchard  of  W.  F.  Stearns,  near  National  City,  California 
(Photograph  by  H.  R.  Fitch,  July  18,  1901) 

hydrocyanic  acid  gas  was  practiced  in  Southern 
California  for  the  disinfection  of  nursery  stock  as 
early  as  1889-90.  Upon  page  479  of  the  '  Report  of 
the  California  State  Board  of  Horticulture  for  1890' 
the  following  reference  to  fumigating  nursery  trees  is 
made  :  '  The  Commission  has  used  the  utmost  vigi- 


224  FUMIGATION   METHODS 

lance  in  causing  all  Flprida  trees  to  be  disinfected  by 
both  dipping  and  gas  treatment.  The  red  scale  of 
Florida,  Aspidiotus  ficus,  has  been  introduced  on  im- 
ported trees,  but  was  without  doubt  eradicated  by  the 
gas  treatment  that  the  trees  received. '  This  is  over  the 
signature  of  F.  Edward  Gray,  at  that  time  one  of  the 
Horticultural  Commissioners  of  L,os  Angeles  County, 
'California.  In  June,  1891,  a  shipment  of  325,000 
oranges  arrived  at  the  Port  of  San  Pedro  from  Tahiti, 
and  were  fumigated  with  hydrocyanic  acid  gas. 

'  *  During  the  above  years  the  county  commissioners 
in  Southern  California  demanded  certificates  that  nur- 
sery stock  had  been  fumigated  or  dipped.  Dr.  L.  O. 
Ho  ward's  history  of  fumigation,  as  printed  in  the  'Year- 
Book  for  1899,  United  States  Department  of  Agricul- 
ture,' is  not  correct.  I  notice  on  page  151  of  that  re- 
port that  he  considers,  in  1894,  ne  was  the  first  to 
recommend  fumigation  of  nursery  stock  before  delivery 
to  purchasers.  I  know  that  previous  to  1894,  as  cited 
above,  that  hundreds  of  thousands  of  nursery  trees  had 
been  fumigated  in  California  before  being  delivered 
to  purchasers.  The  fact  of  the  matter  is  the  United 
States  Department  of  Agriculture  had  practically  noth- 
ing to  do  with  the  discovery  of  the  gas  treatment,  as 
Mr.  Coquillett  was  not  then  in  the  employ  of  the 
Department." 

Fumigate  greenhouses  regularly. — I  fumigate  my 
greenhouses  and  cold  frames  about  four  or  five  times  a 
year  with  it,  and  have  thus  been  able  to  keep  down  all 
insect  and  animal  pests  except  the  red  spider.  How- 
ever, about  80  per  cent,  of  the  red  spiders  are  killed 
by  the  regular  treatment  recommended,  but  to  com- 


ECONOMIC   VALUE   OF   FUMIGATION  225 

pletely  control  the  spider  it  is  necessary  to  use  water 
under  pressure. — Dr.  ALBERT  F.  WOODS,  United 
States  Department  of  Agriculture. 

Olive  trees  fumigated. — In  more  than  a  score  of 
instances  in  Southern  California  olive  trees  have  been 
fumigated  with  the  most  satisfactory  results.  Trees 
which  had  not  borne  fruit  for  several  years,  after  an 
application  of  fumigation,  bore  very  heavy  crops. 
The  olive  trees  had  been  affected  by  black  scale  and 
smut  which  was  totally  destroyed  by  the  application 
of  fumigation.  Peaches,  apricots,  plums,  apples,  and 
pears  fumigated  have  brought  large  crops  and  superior 
fruit,  not  alone  in  flavor  but  also  in  size.  Deciduous 
trees  must  be  fumigated  while  they  are  dormant  before 
the  fruit  buds  or  leaf  buds  begin  to  unfold  or  after  the 
ripe  fruit  has  been  taken  from  the  trees.  This,  in 
fact,  we  consider  the  best  time  to  fumigate.  It  is  a 
serious  blunder  to  neglect  to  avail  one's  self  of  the 
advantages  of  fumigation  in  the  belief  that  it  is  an 
expensive  operation.  Quite  the  contrary  is  the  case. 
It  makes  but  a  small  part  of  the  orchardists'  expense 
while  the  benefits  ramify  in  every  direction. — The 
Rural  Calif ornian. 

Fumigation  understood  and  appreciated. — A  fumi- 
gated tree  conserves  its  energy  and  produces  clean 
fruit,  having  a  brighter  color  and  a  better  flavor  than, 
fruit  which  has  gone  through  the  process  of  washing 
and  cleansing,  and  brings  from  20  to  25  per  cent,  more 
in  price  in  the  market.  The  washing  of  oranges  and 
lemons  to  remove  black,  purple,  or  red  scale  often 
breaks  the  skin  and  spoils  the  appearance  and  flavor  of 


226  FUMIGATION   METHODS 

the  fruit.  Fruit  thafc  has  required  washing  is  fre- 
quently unsalable  when  clean  grown  fruit  is  seen  be- 
side it.  This  is  a  fact  well  understood  and  appreciated 
in  the  districts  where  the  application  of  cyanide  gas  is 
practiced.  Any  one  wishing  to  convince  himself  of  the 
vast  superiority  of  fumigating  over  the  old  spraying 
methods  only  needs  to  visit  the  orchards  of  Duarte, 
Monrovia,  Azusa,  Covina,  Pomona,  and  Riverside, 
and  consult  the  Horticultural  Commissioners.  It  may 
safely  be  stated  that  99  out  of  every  100  of  the  Horti- 
cultural Commissioners  in  the  country  are  heartily  in 
favor  of  fumigation  with  hydrocyanic  acid  gas. — The 
Rural  Calif ornian. 

( '  Does  it  pay  to  fzimigate  ?"  is  answered  by  editor 
C.  M.  Heintz.  He  says:  ' '  This  question  is  asked  daily 
The  Rural  Calif  ornian,  and  we  wish  to  state  that  there 
is  nothing  known  at  present  which  will  assist  the  fruit- 
growers all  over  the  United  States  as  much  to  eradicate 
scale-insect  pest  as  the  process  of  fumigation.  We  in 
California  have  tried  it  for  years,  have  been  benefited 
by  the  operation,  and  permit  us  to  say  if  it  had  not 
been  for  the  fumigation  procedure  the  citrus  fruit  in- 
dustry of  California  would  have  been  a  lamentable 
failure. 

' '  The  actual  and  continuous  use  of  hydrocyanic  acid 
gas  has  demonstrated  beyond  the  question  of  a  doubt 
that  by  exterminating  the  scale  insect  the  citrus  fruit- 
grower has  marketed  a  profitable  crop.  Districts  like 
Riverside,  Ontario,  Pomona,  Azusa,  Orange,  Tustin, 
Colegrove,  San  Dimas,  Lamanda  Park,  and  portion  of 
San  Diego  County,  will  each  testify  to  that  which  we 
state,  namely  ^fumigation  pays,  and  pays  three  hundred- 


ECONOMIC   VALUE-  OF   FUMIGATION  227 

fold.  The  importance  of  freeing  orange  and  lemon 
orchards  of  the  red,  purple,  and  black  scale  at  this 
particular  season  when  the  insects  commence  to  breed 
must  be  obvious  to  every  grower.  It  means  when  the 
shipping  season  opens  healthier  trees,  larger  crop,  and 
gilt-edge  fruit,  and  an  increase  of  receipts. 

' '  These  are  f acts  and  considerations  that  no  com- 
mercial grower  can  ignore,  and  are  of  such  vital  im- 
portance that  unless  conscientiously  practiced  the 
chances  are  five  to  one  that  failure  to  realize  a  profit 
from  his  trees  can  be  traced  directly  to  neglect  in  this 
direction.  We  also  know  that  the  time  has  come 
when  every  nurseryman  in  this  country  will  find  fumi- 
gation a  necessity  in  order  to  keep  clean  his  nursery 
stock,  not  alone  for  his  own  protection,  but  for  his 
customers  as  well." 

In  a  paper  read  recently  by  J.  W.  Jeffrey,  Horti- 
cultural Commissioner,  L,os  Angeles  County,  at  the 
Fruit  Growers'  Convention,  he  said  :  {<  Fumigation  was 
more  universal  last  fall  than  at  any  other  time.  It  has 
been  reduced  to  a  science,  and  while  the  practice  is  not 
always  successful,  poor  work  is  no  longer  tolerated 
without  penalty  upon  the  fumigator.  There  is  little 
complaint  of  impure  cyanide,  but  much  of  its  improper 
applications.  Daylight  applications,  or,  more  prop- 
erly, warm  weather  fumigation,  is  under  ban,  but  a 
few  otherwise  practical  growers  have  not  discovered  it. 
Two  or  three  of  the  leading  citrus  counties  do  this 
work  at  the  treasury's  expense,  afterward  collecting 
from  the  lands  treated.  Los  Angeles  still  requires  the 
orchardists  to  do  their  own  fumigation.  No  new 
scale  pests  have  developed  since  your  last  reports  were 


228  FUMIGATION  METHODS 

out,  nor  is  there  evideftce  that  parasites  have  taken  the 
contract  to  disinfect  the  orchards  of  Southern  Cali- 
fornia." 

The  practice  among  the  fruit-growers  giving  their 
fumigation  to  the  lowest  bidder  is  a  bad  one.  The 
question  should  not  be  how  cheap  you  will  do  it,  but 
how  good  will  you  do  it?  And,  again,  the  work 
should  not  be  let  by  the  tree,  but  by  the  hour.  We 
do  not  deem  it  necessary  to  dwell  upon  the  efficacy  of 
fumigation,  as  we  are  confident  that  no  one  will  dis- 
agree with  us  when  we  say  that  fumigation  has  been, 
and  still  is,  the  salvation  of  the  citrus  fruit  industry 
of  Southern  California. — W.  H.  PAYNE,  Horticultural 
Inspector,  California. 

Recently  The  Rural  Calif ornian  quoted  the  follow- 
ing from  Professor  Cook  :  ' '  Fumigation  has  been  so 
long  and  favorably  known  that  we  do  not  need  to  speak 
its  praises.  *  By  their  fruits  ye  shall  know  them. '  The 
fruits  of  fumigation  are  the  thousands  of  dollars  saved 
to  the  citrus  growers  of  Southern  California. 

'  *  We  must  remember  that  the  foliage  on  orange 
trees  is  very  dense,  even  more  so  than  on  the  lemon, 
and  it  is  not  easy  to  reach  every  scale  insect.  Here, 
as  I  have  often  urged,  is  the  rock  on  which  the  spray- 
ing process  will  split  if  anywhere.  It  is  yet  to  be 
determined  whether  even  in  careful  hands  the  spray 
can  be  thorough  enough  to  be  effective  in  the  orange 
orchard. ' ' 

The  superiority  of  fumigation  with  hydrocyanic  acid 
gas  as  a  remedy  for  the  destruction  of  red,  black,  or,  in 
fact,  almost  any  other  variety  of  scale,  is  no  longer  a 
question  of  doubt  with  people  who  have  tried  all 


ECONOMIC   VAUJE  OF   FUMIGATION  229 

methods  for  the  destruction  of  scale  pests.  The  in- 
creased cost  of  fumigation  over  spraying  has,  however, 
induced  some  orchardists  in  Southern  California  to 
resort  to  the  cheaper  method  of  spraying.  Fumiga- 
tion is  the  only  remedy  considered  at  all  effective  for 
the  red  scale.  The  amount  of  cyanide  required  to 
destroy  black  scale,  if  done  at  the  proper  time,  is  about 
one-half  that  required  for  red  scale.  In  addition  to 
my  duties  as  Horticultural  Commissioner,  I  am  also 
Superintendent  of  Fumigation.  I  have  been  connected 
with  the  horticultural  commission  of  Riverside  County 
for  the  past  six  and  a  half  years. — R.  P.  CUNDIFF. 

Arizona. — In  July,  1900,  I  employed  this  treat- 
ment for  the  destruction  of  the  date  palm  scale,  Parla- 
toria  viflrix,  imported  with  a  large  consignment  of 
some  four  hundred  date-palm  suckers  from  Algeria. 
We  subjected  the  suckers  to  fumigations  varying  from 
0.3  to  0.5  per  cent.  gas.  The  foliage  of  the  plants, 
being  of  exceptionally  hard  and  impervious  nature, 
was  not  injured. — Prof.  R.  H.  FORBES,  Director  Ari- 
zona Experiment  Station. 

Arkansas. — I  am  convinced  that  the  treatment 
with  hydrocyanic  acid  gas  is  an  excellent  method  and 
destined  to  become  of  general  service.  I  have  been 
recommending  it  to  nurserymen  on  occasion,  though 
entirely  on  the  basis  of  knowledge  derived  from  the 
reports  of  others,  such  as  your  own. — Prof.  KRNEST 
WALKER,  Entomologist  Arkansas  Experiment  Station. 

Fumigation  operations  in  Canada. — The  following 
report  was  furnished  the  writer  by  Prof.  William 
L,ochhead,  of  the  Ontario  Agriculture  College :  In 


230  FUMIGATION  METHODS 

Ontario  we  are  operating  under  the  San  Jose  Scale 
Ammendment  Act,  passed  April  i,  1899,  Legislature 
of  Ontario,  and  the  following  are  the  chief  clauses  or 
sections  relating  directly  to  the  inspection  and  fumi- 
gation of  nursery  stock: 

Portion  of  the  San  Jos / Scale  Act. — The  following 
are  the  sections  of  the  San  Jose  Scale  Act  dealing 
with  the  fumigation  of  nursery  stock,  62d  Victoria, 
Chapter  35: 

3.  No  person  shall  import  or  bring,  or  cause  to  be  imported 
or   brought,  into  the  Province  of    Ontario,  for  any  purpose 
whatsoever,  any  plant  infested  with  scale. 

4.  No  person  shall  keep,  or  have,  or  offer  for  exchange  or 
sale,  any  plant  infested  with  scale,, 

5.  The  owner  or  proprietor  of  any  nursery  shall  not  send 
out,  or  permit   any  plant  to  be   removed,   from  his  nursery, 
without  the  same  first  being  fumigated  by  hydrocyanic  acid 
gas,  in  accordance  with  regulations  prescribed  by  order  of  the 
Lieutenant-Governor-in-Council.     62  Vic.,  Chap.  35. 

6.  No  person  shall  sell,  or  dispose  of,  or  offer  for  sale, 
any  plant  obtained,  taken  or  sent  out  from  a  nursery  unless 
the  said  plant  has  previously  been  fumigated  in  accordance 
with  these  regulations.     62  Vic.,  Chap.  35. 

7.  In  case  the  Inspector  finds  scale  in  any  nursery  and  so 
reports  to  the  Minister,  the  Minister  may  thereupon  inform, 
by    writing,    the   owner   or   proprietor   or    manager    of   said 
nursery   of   the    existence    of    scale    in  his    nursery,  and  the 
owner   or  proprietor  or   manager  of   said  nursery  shall   not 
thereafter  permit  any  plant  or  plants  to  be  removed  from  the 
said  nursery  until  the  Inspector  reports  to  the  Minister  that 
it  is    safe  in   the   public    interest  to  permit   the  said   nursery 
stock  to  be  removed  after  fumigation.     62  Vic.,  Chap.  35. 

Canadian  fumigation  regulations. — The  following 
regulations  have  been  prescribed  by  order  of  the 


ECONOMIC  VALUE  OF   FUMIGATION  231 

Lieutenant- Governor  in  Council,  in  accordance  with 
the  provisions  of  the  San  Jose  Scale  Amendment  Adi, 
passed  April  i,  1899  : 

1.  Fumigation  must  be  carried  on  in  a  box,  room,  com- 
partment, or  house,  suitable  for  the  purpose,  which  must  be 
air-tight   and    capable   of   rapid    ventilation.     The   owner   or 
proprietor  will  notify  the  Minister  as  soon  as  preparation  for 
fumigation  is  complete.     The   Minister  will  thereupon  order 
an  inspection  of  the  fumigation  appliances.     No  fumigation 
under  the  Act  is  to  be  carried  on  until  such  inspection  has  been 
made  and  a  satisfactory  report  sent  to  the  Minister. 

2.  The  Inspector,  after  examining  and  measuring  the  box 
or  house,  or  other  compartment  in  which  fumigation   is  to  be 
carried  on,  will  prescribe  the  amounts  of  material  to  be  used 
for   every    fumigation,  and   the    instructions  as  to  the   same 
must    be    carefully    followed    out.      The    Inspector    may.    if 
thought  advisable,  supply  the  material  for  each  fumigation  in 
weighed  packages. 

3.  The  fumigation  house  (which  shall  include  all  apparatus 
or  appliances  used  in  the  fumigation,  such  as  generators,  etc.) 
is  to  be  subject  to  the  orders  of  the  Minister  on  the  recom- 
mendation of  the  Inspector.     Subject  to  the  approval  of  the 
Inspector,  the  fumigation  house  may  be  on  other  lots  than 
those  on  which  the  nursery  stock  are  growing. 

*^.'  The  fumigation  is  to  be  by  hydrocyanic  acid  gas,  pro- 
duced according  to  the  instructions  of  the  Inspector  and  from 
such  formulas  as  he  prescribes  for  the  purpose. 

5.  The  fumigation  is  to  be  continued  for  a  period  of  not 
less   than    forty-five    minutes.     After   the    expiration    of  this 
time,  or  longer,  and  when  fumigation  is  complete,  the  house 
is  to  be  thoroughly  ventilated  for  fifteen  minutes  at  least. 

6.  No   person    is  to  be  allowed  to  enter  the   fumigating 
house  until  after  the  ventilation   period  has  expired.     Enter- 
ing before  may  prove  injurious,  if  not  fatal,  as  the  gas  is  a 
deadly  poison. 

7.  The  fumigation  of  buds  and  scions   may  be  done    in 


232  FUMIGATION  METHODS 

fumigation  boxes  of  not  lots  than  thirty  cubic  feet  capacity, 
the  same  to  be  subject  to  inspection  and  approval. 

8.  Immediately  after  inspection  of  the  fumigation  house 
the  Inspector  will  report  to  the  Minister,  and  the  Minister  or 
Inspector  will  thereupon  give   permission   in  writing  for  the 
owner  or  proprietor  to  begin  fumigation. 

9.  The  owner  or  proprietor  of  every  nursery  will  attach 
to  every  box  and  to  every  package  of  nursery  stock  a  certificate 
as  follows,  and  he  will  furnish  every  purchaser  who  so  desires 
a  copy  of  the  same: 

Certificate  of  fumigation. — This    is    to    certify    that    this 

package    of    nursery    stock,    consisting    of was 

properly  fumigated  on  or  about  the day  of 

1901,  in  accordance  with  the  regulations  prescribed  by  order 
of  the  Lieutenant-Governor-in-Council,  in  accordance  with 
62d  Victoria,  Chapter  35. 

Amount  of  nursery  stock  fumigated. — We  have  in 
Ontario  117  names  on  the  nursery  list,  but  probably  it 
would  be  more  nearly  correct  to  say  that  there  are  not 
more  than  100  different  nurserymen  in  Ontario,  about 
four-fifths  of  the  work  being  done  by  five  or  six  of  the 
largest  nurserymen.  Three  out  of  every  four  nursery- 
men on  the  list  do  nothing  more  than  a  local  business, 
but  the  four  or  five  large  concerns  handle  an  immense 
amount  of  stock.  It  is  somewhat  difficult  to  get  informa- 
tion from  Canadian  nurserymen  regarding  the  amount  of 
stock  fumigated.  However,  one  large  nurseryman 
wrote  me  as  follows :  "  It  is  a  hard  matter  to  give 
any  accurate  report  as  to  the  number  of  trees  put 
through  our  fumigation  house  in  a  year,  but  would 
estimate  that  the  trees  would  be  about  as  follows  : 
200,000  apples,  25,000  pears,  40,000  plums,  35,000 
cherries,  50,000  peaches,  50,000  ornamental  trees  and 
shrubs,  135,000  small  fruits — making  a  total  of  535,- 


ECONOMIC  VALUE  OF   FUMIGATION  233 

ooo."  There  are  four  nurserymen  doing  business 
almost  as  large  as  the  one  quoted.  On  the  supposi- 
tion that  these  four  nurseries  have  about  the  same  out- 
put and  that  they  do  four-fifths  of  the  total  business  of 
the  province,  the  amount  of  stock  sent  through  Ca- 
nadian fumigation  houses  would  be  in  the  neighbor- 
hood of  two  and  a  half  million  trees. 

Fumigation  in  Ontario  has  been  limited  almost 
altogether  to  nursery  stock,  and  practically  nothing 
has  been  done  on  orchard  trees.  As  far  as  the 
work  in  the  nursery  is  concerned,  I  can  say  candidly 
that  I  am  much  pleased  with  the  results.  No  trace 
of  scale  has  yet  been  found  on  stock  which  has  been 
fumigated.  It  is  true  that  the  first  year  the  Act 
was  in  operation  houses  were  built  very  hurriedly 
and  frequently  in  a  slipshod  manner,  and  fumiga- 
tion was  also  performed  in  a  half-hearted  and  be- 
grudging manner  by  the  nurserymen,  but  I  have 
found  no  trace  of  scale  on  nursery  stock  sent  out  that 
year.  I  have  made  no  improvement  over  the  methods 
and  equipment  outlined  by  yourself.  I  still  follow 
your  formula  as  amended  and  your  method  of  con- 
structing fumigation  houses.  Of  course,  individual 
nurserymen  may  have  special  contrivances  for  fixing 
the  door  and  providing  ventilation.  I  find  by  expe- 
rience that  the  doors  and  windows  are  the  parts  of  the 
house  which  are  most  apt  to  get  out  of  repair. 

Dr.  James  Fletcher,  Dominion  Entomologist,  who 
has  had  charge  of  the  fumigation  houses  at  the  ports 
of  entry,  writes  that  in  the  fumigation  of  the  nursery 
stock  in  boxes  at  the  border  every  bit  of  packing  right 
down  to  the  roots  is  removed,  and  only  the  roots  are 


234  FUMIGATION   METHODS 

allowed  to  be  covered..   He  has  found  no  instance,  as 
yet,  of  living  scale  on  any  such  treated  stock. 

Orchard  fumigation. — One  of  Canada's  fruit  grow- 
ers writes  Professor  Lochhead  regarding  the  application 
of  the  tent  system  of  fumigation  on  small  orchard  trees 
as  follows  :  "  We  took  a  common  apple  barrel,  mak- 
ing it  fit  the  trees  by  using  a  width  of  ten- cent  factory 
cotton  well  soaked  in  linseed  oil,  and  while  wet  tacked 
it  on  the  barrel.  When  dry  it  seemed  to  adhere  to 
the  barrel,  making  it  practically  air-tight.  Then  I 
headed  back  the  three-year-old  plum  trees,  so  as  to 
drop  the  sacks  over  them.  For  large  trees  we  made 
tents  6x7x9  feet  high,  with  posts  at  each  end  and 
sills  and  plates,  these  being  well  braced  both  horizon- 
tally and  perpendicularly.  Then  I  made  a  door, 
fastened  to  one  post  by  three  hinges,  and  shut  to  next 
post  by  a  bolt  in  center  and  buttons  at  the  top  and 
bottom.  I  measured  out  factory  cotton  twenty-six 
inches  long  and  sewed  three  widths  together.  This 
was  oiled  and  tacked  on  while  wet.  We  put  on 
top  piece  first  with  tacks,  then  commenced  side  cover- 
ings where  the  door  shuts,  and  brought  it  right  around 
the  frame,  letting  it  lap  two  inches  on  top  and  leave  a 
balance  of  ten  inches  to  lay  on  ground,  which  is  cov- 
ered with  earth.  Then  a  common  lath  is  nailed  over 
the  lap  all  around  the  top.  When  complete  cut  out 
the  hole  on  the  side  the  door  hinges  on,  to  allow  the 
tent  to  pass  over  the  tree.  This  will  require  three 
days  to  dry  properly.  Trees  treated  with  the  last  tent 
were  eight  years  old  and  had  borne  four  crops  of  fruit. 
We  had  to  head  them  back  considerably.  It  takes 
three  men  to  handle  these  large  tents,  but  one  man 


ECONOMIC  VALUE   OF   FUMIGATION  235 

can  handle  the  small  ones  nicely.  In  fadl,  three  men 
could  manage  ten  large  tents  in  one  hour.  From 
every  appearance  now  the  scale  seems  to  be  thoroughly 
killed  and  the  trees  to  be  do:ng  well." 

Certificate  of  fumigation. — Professor  lyochhead  says  : 
' '  In  Ontario  there  is  one  particular  in  which  we  differ 
from  most  of  the  states  to  the  south  of  us,  and 
that  is  in  allowing  the  proprietor  of  every  nursery 
to  attach  his  own  certificate  of  fumigation.  Per- 
sonally, I  think  this  is  neither  fair  to  the  nurserymen 
nor  to  the  public,  but  the  Department  of  Agriculture 
here  in  Ontario  has  never  seen  fit  to  appoint  official 
fumigators  to  take  charge  of  the  fumigation  at  every 
nursery.  The  department  allows  the  nurseryman  to 
do  his  own  fumigating  and  to  attach  a  certificate  of 
fumigation  to  every  package  sent  out.  The  inspector, 
of  course,  and  his  assistants  are  moving  about  during 
fumigation  time,  and  the  nurseryman  does  not  know 
when  to  expect  a  visit.  Of  course,  we  look  after  those 
nurseryman  who  live  in  infested  regions.  All  the 
nurseries  in  the  scale-infested  regions  are  examined  for 
scale,  so  that  there  is  a  double  check  on  all  stock  sent 
out." 

Nurserymen  willing  to  fumigate. — "I  find  that 
there  is  quite  a  change  of  opinion  regarding  the  merits 
of  fumigation  within  the  past  year.  I  can  say  now, 
without  hesitation,  that  nearly  every  nurseryman  is 
perfectly  willing  to  fumigate  his  stock  according  to 
directions,  and  to  do  it  carefully.  He  feels  that  his 
reputation  and  his  business  are  at  stake  should  scale  be 
found  on  his  stock.  We  examine  every  fumigation 


236  FUMIGATION   METHODS 

house  twice  a  year,  aud  we  test  it  with  smoke  before 
we  allow  it  to  be  used,  in  order  to  show  the  position  of 
any  possible  leakage.  For  the  first  two  years  one  or 
two  nurserymen  blamed  fumigation  for  the  death  of 
many  of  their  peach  trees,  but  they  have  now  become 
convinced  that  the  damage  was  done  by  the  very  severe 
winter  of  1898-99." 

Connecticut. — I  have  not  used  the  gas  against  San 
Jose  scale,  but  have  examined  stock  which  had  been 
fumigated  and  could  find  no  living  specimens  a  year 
later.  We  have  used  the  gas  in  the  tomato  forcing 
house,  using  3  and  2^  ounces  of  cyanide  per  1,000 
cubic  feet  of  space  to  kill  white  fly,  Alerodes  vaporarioum 
Westwood.  The  plants  were  slightly  injured  at  the 
top  and  every  insect  killed.  Have  also  tried  it  in  a 
barn  to  kill  the  clover-hay  worm,  Pyralis  co stalls. — 
Prof.  W.  K.  BRITTON,  State  Entomologist,  Connecticut. 

Florida. — The  following  timely  account  of  the 
work  in  Florida  has  been  furnished  us  by  Prof.  S.  A. 
Gossard,  Entomologist  of  the  Experiment  Station: 
"  We  commenced  some  extensive  experimentation  in 
fumigating  orange  trees  for  white  fly,  Alerodes  citri,  in 
1900.  We  found  that  the  treatment  destroyed  the 
insects — in  fact,  practically  exterminated  them — with 
smaller  charges  than  are  used  by  the  California  people. 
Most  of  our  work  was  done  in  the  daytime,  and 
while  I  have  not  seen  the  treated  trees  for  several 
weeks  a  report  by  letter  indicates  that  they  are  all 
right  and  have  a  good  set  of  fruit.  The  trees  dropped 
from  one-fourth  to  nearly  all  of  their  leaves,  but  put 
out  again  immediately  and  seem  to  have  a  good  set  of 


ECONOMIC   VALUE   OF   FUMIGATION  237 

fruit.  It  would  appear,  therefore,  that  dropping  the 
leaves  from  the  trees  is  not  so  apt  to  work  injury  to 
the  orange  in  Florida  as  in  California.  We  fumigated 
trees  of  various  sizes  from  mere  bushes  up  to  30 
feet  in  hight  and  25  feet  in  diameter,  using  various 
styles  of  tents.  The  hoop  tent  proved  most  satis- 
factory for  trees  not  over  12  feet  in  hight  and  of 
equal  diameter,  but  for  larger  trees  we  used  the  bell 
tent,  handling  it  by  means  of  a  new  form  of  derrick. 
We  ceased  fumigation  work  when  the  trees  com- 
menced to  blossom  freely,  and  put  the  tents  away. 

"  Several  hundred  trees  were  fumigated,  and  four  or 
five  times  as  many  sprayed  with  resin  wash  and  with 
a  few  other  materials  for  comparison.  The  gas  method 
is  the  more  expensive  to  begin  with,  but  we  are  inclined 
to  believe  it  may  be  the  cheapest  in  the  end.  I  found 
that  about  seventy -five  per  cent,  of  the  insects  were 
killed  by  a  single  spraying  with  resin  wash,  but  in 
examining  thousands  of  insects  upon  many  different 
trees  that  were  fumigated  I  was  able  to  find  but  a 
single  living  representative.  I  have  no  doubt  that  the 
practical  application  of  the  process  to  two  or  three  of 
our  orange-growing  counties  will  mean  a  net  profit  of 
$250,000  to  $500,000  annually  inside  of  three  or  four 
years,  if  the  treatment  is  generally  adopted.  We  have 
not  worked  with  deciduous  trees,  not  because  we 
believe  it  impracticable,  but  for  lack  of  time  up  to  the 
present.  A  number  of  our  nurserymen  use  the  gas  in 
fumigating  their  nursery  stock,  and  in  a  more  limited 
way  plants  and  shrubs,  upon  their  premises.  Nearly 
all  of  our  nurserymen  doing  a  large  and  extensive 
business  have  excellent  fumigating  appliances. 


238  FUMIGATION   METHODS 

"  One  form  of  fumigating  box  in  use  by  some  of 
our  nurserymen  deserves  notice.  It  consits  of  a 
smaller  box  resting  inside  of  a  larger  one,  about  six 
inches  of  space  separating  the  two  between  the  bot- 
toms and  about  the  sides,  which  is  filled  with  loose 
sand  or  clay.  The  top  is  either  constructed  with  a 
similar  space  filled  in  with  sand  or  earth,  or  may  be  of 
the  usual  pattern  double-boarded  with  tarred  paper 
between.  This  lid  has  a  rim  of  beveled  inch-board  six 
inches  deep,  projecting  downward  and  falling  into  the 
sand  above  mentioned,  being  brought  perfectly  into 
place  by  a  wooden  wedge  above.  This  produces  a  box 
that  is  absolutely  air-tight,  and  can  never  have  an 
unsuspected  leak  of  any  kind  in  it. 

"  Judging  from  the  evidence  in  my  office,  the  gas 
treatment  carefully  applied  is  absolute  protection 
against  San  Jose  scale  and  other  insect  pests  upon 
nursery  stock.  I  have  known  instances  where  much 
nursery  stock  had  gone  forth  infested  when  fumiga- 
tion was  either  not  practiced  at  all  or  was  carelessly 
done,  but  have  failed  to  learn  of  a  single  case  of 
infested  stock  going  out  from  the  same  nurseries  after 
the  stock  was  carefully  treated." 

Idaho. — No  experimental  work  with  hydrocyanic 
gas  has  been  done  at  this  station.  The  question  of 
infested  nursery  stock  has  not  been  a  pressing  one. 
In  this  state  I  knew  of  one  infested  nursery,  but  it 
was  abandoned.  The  owner  made  some  inquiries  of 
me  about  the  subject  of  fumigation,  and  constructed  a 
fumigating  room,  which  he  used  for  a  year  or  two 
with  success.  As  to  fumigation  of  commercial 
orchards,  there  has  been  none  of  it  here  so  far 


ECONOMIC  VALUE  OF  FUMIGATION      239 

as  I   know. — Prof.    J.    M.    ALDRICH,    University    of 
Idaho. 

Louisiana. — We  are  much  interested  in  the  use 
of  this  gas.  Some  fumigation  of  orange  trees  was 
made  a  few  years  ago,  as  noted  in  a  special  bulletin 
from  the  Louisiana  Kxperiment  Station  entitled,  ' '  In- 
sects of  Orange."  We  have  used  hydrocj^anic  acid 
gas  with  good  results  for  the  cow-pea  or  bean  weevil. 
The  cow-peas  were  stored  in  a  closed  room  and  the 
amount  of  cyanide  used  was  according  to  your  own 
formula.  We  have  arranged  to  fumigate  plants  com- 
ing into  Louisiana,  and  it  is  our  intention  to  use  the 
gas  much  more  extensively. — Prof.  H.  A.  MORGAN, 
Entomologist  Louisiana  Experiment  Station. 

Massachusetts. — My  candid  opinion  as  to  the  effi- 
ciency of  the  gas  method  for  the  destruction  of  insects 
is  that  it  should  be  much  more  widely  used,  but  only 
by  experienced  hands.  I  believe  it  to  be  available  for 
the  fumigation  of  greenhouses,  warehouses,  and  other 
places,  but  do  not  believe  in  its  use  where  carbon  bisul- 
phide will  do  the  work,  considering  the  latter  to  be 
safer.  The  Kxperiment  Station  is  strongly  in  favor  of 
fumigation,  but  in  the  absence  of  any  law  on  the  sub- 
ject can  only  make  use  of  moral  suasion. — DR.  H.  T. 
FERNALD,  Associate  Entomologist,  Hatch  Experiment 
Station,  Massachusetts. 

In  Michigan  cheap  and  reliable. — We  now  have 
excellent  spraying  laws  and  others,  requiring  the 
inspection  of  nurseries  and  orchards  for  San  Jose  scale 
and  other  dangerous  insects  and  diseases,  but  it  has  not 
been  found  necessary  to  require  the  fumigation  of  all 


240  FUMIGATION   METHODS 

nursery  stock.  The  San  Jose  scale  has  only  secured  a 
foothold  in  a  few  localities,  and  even  there  has  been 
confined  to  comparatively  small  areas.  So  far  as  is 
known,  there  is  no  San  Jose  scale  within  several  miles 
of  any  of  our  nurseries.  In  one  or  two  instances  fumi- 
gation has  been  required  where  the  black  peach  aphis 
has  been  found  in  a  nursery,  and  under  our  present  law 
it  will  be  possible  to  compel  nurserymen  to  fumigate 
their  stock  before  it  is  sent  out  if  the  scale  is  found  in 
a  nursery,  or  in  such  close  proximity  that  there  is  a 
possibility  that  the  trees  may  be  infested,  even  though 
careful  inspection  fails  to  reveal  its  presence.  In  case 
the  scale  continues  to  spread  a  move  will  be  made  to 
secure  a  compulsory  fumigating  law  that  will  apply  to 
all  nurseries.  At  the  present  time  it  seems  the  cheapest 
and  most  reliable  method  of  treating  nursery  stock,  as 
well  as  for  the  destruction  of  many  insects  that  are  found 
in  buildings. — Prof.  L,.  R.  TAFT,  Michigan  Agricul- 
tural College. 

Urges  law  in  Mississippi. — There  has  never  been 
anything  done  with  hydrocyanic  acid  gas  in  this  state. 
We  have  no  laws  on  fumigation  of  nursery  stock,  but 
I  have  been  urging  laws,  and  think  I  shall  present  the 
matter  to  the  legislature. — Prof.  GLENN  W.  HERRICK, 
Entomologist  Mississippi  Experiment  Station. 

Successful  mill  fumigation  in  Missouri. — Some  nur- 
series have  erected  a  fumigating  house  and  have  fumi- 
gated both  the  material  entering  and  leaving  the 
nursery,  but  no  one  knows  that  it  ever  had  the  San 
Jose  scale  in  any  case.  Some  greenhouses  have  also 
been  fumigated,  and  always  with  success,  but  of  course 


ECONOMIC  VALUE   OP   FUMIGATION  241 

this  was  for  the  ordinary  greenhouse  inse<5l  pests.  I 
have  never  fumigated  nursery  stock  or  trees  that  had 
the  San  Jose  scale  with  hydrocyanic  acid  gas  and  then 
made  careful  tests  to  see  if  all  scales  were  killed,  and 
hence  I  can  not  speak  on  that  point.  Several  mills  in 
this  state  have  been  fumigated  with  this  gas,  and  with 
success,  but  it  is  difficult  to  get  the  mills  aired  out 
properly  without  danger,  unless  special  arrangements 
be  made  to  do  this  from  the  outside.  This  state  has 
no  fumigation  laws,  and  probably  will  not  for  some 
time.  We  have  only  just  succeeded  in  getting  a  law 
passed  requiring  stock  entering  the  state  to  bear  certi- 
ficate of  inspection. — Prof.  J.  M.  STEADMAN,  Univer- 
sity of  Missouri. 

Nebraska  fumigates  doubtful  stock. — Although  we 
have  done  comparatively  little  in  the  way  of  using 
hydrocyanic  acid  gas  for  the  purpose  of  fumigating 
nursery  stock,  a  little  has  been  done  in  this  direction, 
chiefly  by  our  nurserymen  when  they  receive  stock 
from  abroad  about  which  they  feel  a  little  dubious. — 
Prof.  LAWRENCE  BRUNER,  University  of  Nebraska. 

North  Carolina. — I  think  that  it  is  only  a  question 
of  a  very  short  time  before  fumigation  will  be  one  of 
the  regular  operations  of  the  nurseryman.  Where 
there  are  great  interests  at  stake,  I  do  not  think  that 
laws  compelling  fumigation  are  out  of  place  but 
rather  a  necessity.  Most  people  are  too  much  inclined 
to  look  upon  fumigation  requirements  only  with 
reference  to  San  Jose  scale.  It  seems  to  me  that  it  is 
equally  fatal  to  other  insects,  and  it  cannot  fail  to  be 
of  very  great  benefit  to  the  fruit  grower.  The  cost  of 


242  FUMIGATION   METHODS 

fumigation  to  the  nurseryman,  as  compared  with  the 
cost  to  the  grower,  for  spraying,  etc.,  is  very  small. 
Of  course  a  system  of  fumigation  will  not  do  away 
with  the  necessity  of  spraying  in  orchards,  but  it  will 
greatly  decrease  the  loss  that  growers  now  sustain 
from  the  attacks  of  various  insects. — Prof.  FRANKLIN 
SHERMAN,  Jr.,  State  Entomologist,  North  Carolina. 

North  Dakota  fumigated  palms. — Owing  to  the  fact 
that  the  number  of  fruit  trees  grown  in  this  state  is 
very  small,  and  that  scale  and  other  insedls  have  not 
yet  appeared,  its  use  has  not  become  general.  I  have 
used  the  gas  with  very  satisfactory  results  at  this  sta- 
tion to  kill  the  scale  on  palms.  I  have  known  of  its 
use  with  equally  good  results  in  the  destruction  of  bed- 
bugs in  houses.  — C.  B.  WA^DRON,  North  Dakota 
Agricultural  College. 

New  Jersey. — Personally  I  have  done  so  little  with 
the  hydrocyanic  acid  gas  that  I  do  not  consider  my- 
self entitled  to  any  opinion  as  to  its  value,  i.e.,  no 
opinion  formed  as  the  results  of  original  work.  The 
truth  is,  I  never  like  to  duplicate  another  man's  work, 
and  as  you  have  been  doing  the  fumigation  line  most 
thoroughly  I  was  willing  to  accept  your  results,  de- 
voting my  time  to  other  lines  of  investigation. — Dr. 
JOHN  B.  SMITH,  State  Entomologist,  New  Jersey. 

New  York. — I  have  not  had  much  experience  in  the 
use  of  hydrocyanic  acid  gas  on  nursery  stock,  but  from 
what  I  have  used  and  from  what  I  know  of  it  in  other 
respects,  it  seems  to  me  to  be  one  of  the  very  best  and 
perhaps  the  only  satisfactory  method  of  treating  young 
trees  for  the  purpose  of  killing  insect  pests  upon  them. 


ECONOMIC  VALUE  OF  FUMIGATION      243 

Were  I  to  buy  trees  for  personal  use  I  should  most  cer- 
tainly insist  upon  their  being  fumigated,  especially  if  the 
grounds  of  my  neighbor  were  badly  infested  with  San 
Jose  scale.  I  believe  fumigation  is  a  good  thing  aside 
from  any  suspicion  of  the  presence  of  the  San  Jose 
scale,  because  it  enables  a  man  to  start  his  trees  as  free 
from  insect  pests  as  perhaps  any  process  through  which 
he  could  put  them. — Dr.  E.  P.  FELT,  State  Entomolo- 
gist',  New  York. 

Ohio. — I  have  not  had  any  reason  to  change  my 
former  opinion  as  to  its  efficiency.  Used  at  the  proper 
season,  I  do  not  know  that  there  is  the  least  danger  to 
nursery  stock,  and  I  do  not  believe,  if  properly  used, 
it  is  possible  for  a  scale  insect  to  pass  through  a  fumi- 
gating house  alive.  We  may  say,  as  among  other 
things  connected  with  nursery  work,  and,  in  fact,  every- 
thing else,  much  depends  upon  whether  fumigating  is 
done  properly  or  improperly.  All  of  the  houses  that  I 
have  had  built  have  been  provided  with  slat  floors  and 
we  have  generated  the  gas  underneath.  I  find  this  is 
much  more  practical  than  any  other  way  that  I  have 
tried.  Of  course  for  very  small  nurseries  we  have 
advocated  a  tight  box,  but  this  is  only  where  plants 
like  raspberries  and  blackberries  are  fumigated. — Prof. 
F.  M.  WEBSTER,  Entomologist  Ohio  Experiment 
Station. 

Pennsylvania. — I  have  not  made  a  thorough  canvass 
of  our  state  in  regard  to  the  use  of  hydrocyanic  acid 
gas,  but  know  that  many  of  our  nurseries  have  con- 
structed fumigating  houses  and  are  carefully  subjecting 
infested  stock  to  the  gas  treatment.  This  treatment  is 


244  FUMIGATION   METHODS 

the  most  effectual  method  we  have  to  clean  up  nursery 
stock  of  its  insect  pests,  and  has  given  great  satisfaction 
where  it  has  been  judiciously  handled.  There  are 
cases  in  which  the  exposure  to  the  gas  was  unneces- 
sarily long,  resulting  in  marked  injury  to  the  trees. 
It  is  useless,  of  course,  to  subject  trees  to  the  gas  which 
are  free  from  insects.  The  gas  treatment  should  find 
favor  in  warehouses,  flour-mills,  etc.,  where  vermin 
are  to  be  destroyed  and  no  life  is  at  stake,  but  I  have 
met  with  no  experience  in  such  places.  I  cannot 
recommend  it  for  conservatories  or  greenhouses  where 
a  mixed  lot  of  plants  are  grown.  In  my  own  experi- 
ence I  have  found  many  kinds  of  plants  suffer  greatly 
in  an  exposure  that  is  too  weak  and  brief  to  kill  all  of 
the  red  spiders  or  mealy  bugs.  If  a  single  house  can 
be  closed  off  and  the  stock  is  wholly  of  one  kind  of 
plants,  as  violets  or  chrysanthemums  or  carnations,  it 
is  possible  to  so  adjust  the  treatment  that  no  injury  will 
befall  the  plants  and  the  insects  will  be  destroyed.— 
Prof.  GEORGE  C.  BUTZ,  Horticulturist  Pennsylvania 
Agricultural  Experiment  Station. 

Rhode  Island. — I  believe  that  the  gas  treatment  for 
the  destruction  of  insects  upon  nursery  stock  is  the 
only  efficient  method  for  the  destruction  of  certain  of 
the  pests,  and  personally  were  I  to  buy  plants  for  a 
large  orchard,  or  for  use  in  the  orchards  which  I 
already  have  planted  which  are  now  free  from  San  Jos6 
scale,  I  would  most  surely  buy  them  from  some 
nursery  which  would  fumigate  trees  before  shipment. 
I  believe  that  as  the  efficiency  of  this  method  of  treat- 
ment is  more  fully  understood  and  appreciated  by 
warehouse  and  flour-mill  owners  that  this  will  become 


ECONOMIC   VALUE   OF   FUMIGATION  245 

the  method  in  vogue  for  the  destruction  of  insects 
which  harbor  in  such  buildings. — G.  K.  ADAMS, 
Assistant  Horticulturist  Rhode  Island  Experiment  Sta- 
tion. 

Virginia. — In  my  several  bulletins  on  the  San  Jose" 
scale  and  reports  as  state  inspector  for  the  same,  I 
have  mentioned  more  or  less  frequently  the  subject  of 
fumigation.  We  have  never  attempted  fumigating 
orchards  or  plants  of  any  kind,  except  nursery  stock 
in  closed  houses.  Our  present  formula  to  each  100 
cubic  feet  of  space  in  room  for  fumigating  nursery 
stock  is  as  follows:  Fused  potassium  cyanide,  98  per 
cent.,  i  ounce;  commercial  sulphuric  acid,  high  grade, 
i1/;.  fluid  ounces;  water,  3  fluid  ounces.  This  has 
proved  very  satisfactory,  and  thus  far  we  have  no 
instance  in  which  it  has  damaged  the  stock.  I  am 
happy  to  say  no  instance  has  come  to  our  notice  in 
which  the  scale  has  survived  treatment  by  the  above 
formula. — Prof.  WILLIAM  B.  ALWOOD,  State  Ento- 
mologist, Virginia. 

Sound  Advice. — In  an  address  before  the  New  York 
Fruit  Growers'  Association,  L,.  T.  Yeomans,  a  prom- 
inent New  York  fruit-grower,  said:  "Our  firm  has 
not  planted  a  tree  during  the  past  two  years  which 
has  not  been  fumigated  with  hydrocyanic  acid  gas. 
We  do  the  work  ourselves  cheaply,  quickly,  and  with- 
out injury  to  even  peach  trees,  notwithstanding  the 
assertion  of  some  nurserymen  that  it  is  unsafe,  ex- 
pensive, and  dangerous.  A  nurseryman  in  western 
New  York  who  has  fumigated  for  several  years  all  the 
nursery  stock  he  sells,  says  the  expense  to  him  does 


246  FUMIGATION   METHODS 

not  exceed  25  cento  per  1,000  trees  of  regular  one 
dollar  size.  If  all  planters  would  refuse  to  buy  trees 
which  had  not  been  fumigated,  the  nurserymen  would 
see  it  for  their  interest  to  fumigate.  I  am  happy  to 
say  that  there  are  some  nurserymen  who  fumigate  all 
their  stock.  No  trees  can  be  shipped  into  Canada 
without  fumigation,  and  yet  there  are  some  who  raise 
a  cry  about  the  hardships  it  would  be  for  them  if  com- 
pelled to  fumigate  stock  sold  to  the  grower,  yet  these 
same  nurserymen  find  it  to  their  interests  to  comply 
with  the  Canadian  law  rather  than  abandon  their 
trade  across  the  border. ' ' 

Views  of  a  practical  fruit  grower  and  nurseryman. 
— The  following  statement  was  received  from  C.  M. 
Hooker,  the  senior  member  of  the  well-known  nursery 
firm  Hooker,  Wyman  &  Co.,  of  Rochester:  "I  am 
strongly  in  favor  of  the  fumigation  of  all  nursery  stock, 
when  it  can  be  safely  done,  before  dissemination  or 
planting.  This  should  be  done  by  the  nurseryman,  but 
to  be  perfectly  safe  I  personally  fumigate  all  stock 
planted  on  our  place.  I  have  done  so  for  years,  and  can- 
not afford  to  take  any  risk  of  infestation  of  San  Jose 
scale  from  the  carelessness  of  others.  That  nursery 
stock  should  be  fumigated  before  planting  is  evident 
from  the  rapid  spread  of  this  pest  when  it  is  neglected 
and  the  serious  loss  of  all  those  who  plant  infested  stock. 
All  infested  nurseries  should  be  compelled  to  fumigate 
their  stock  if  the  people  are  to  be  safe  in  buying  their 
trees. 

Answers  objeftors. — "The  objections  which  are 
made  to  a  law  requiring  fumigation  by  some  nursery- 
men I  think  are  not  of  great  force. 


ECONOMIC  VALUE   OF   FUMIGATION  247 

"is/.  They  object  to  the  cost.  We  reply  that  it  is 
proven  that  it  is  not  over  25  cents  per  1,000  trees. 

"  2d.  Delay  of  shipment.  This  cannot  be  over  a 
few  hours. 

"3^.  Nobody  knows  that  the  process  is  effectual. 
Many  tests  prove  that  it  is  the  best  known  and  never 
fails  if  properly  done. 

"4^.  Dangerous  to  employees.  No  one  was  ever 
seriously  injured  by  the  gas,  and  with  a  little  care  it  is 
perfectly  safe. 

"5^.  Inspection  is  sufficient.  This  has  been  proven 
a  failure  in  many  cases.  Of  course,  inspection  is 
necessary  and  good  so  far  as  it  goes,  especially  in 
locating  the  pest  in  nurseries  and  orchards. 

"  6th,  Dangerous  to  nursery  stock.  This  does  not 
prove  to  be  the  case  when  properly  conducted.  One 
nursery  firm  in  Geneva  has  fumigated  over  one  million 
trees  without  damage  to  one. 

' '  7/A.  Wait  for  a  federal  law.  Of  course  this  is  only 
an  excuse  for  delay.  We  shall  never  get  a  federal 
law,  and  in  any  event  should  take  care  of  our  own  scale. 

"  8M.  Not  constitutional.  Give  us  the  law,  and 
we  will  risk  that. 

"  gth.  Other  states  will  retaliate  by  passing  similar 
laws.  Well,  we  are  not  certain  what  other  states  may 
do,  but  we  should  do  what  is  right  to  protect  our 
state  from  the  San  Jose  scale  and  let  other  states  do 
what  they  think  best  for  their  interests.  There  are 
other  and  more  important  interests  than  the  nursery 
interests,  yet  it  certainly  is  for  the  interests  of  the 
nurserymen  to  keep  New  York  State  as  free  as  possi- 
ble from  the  scale. 


248  FUMIGATION   METHODS 

"  loth.  It  is  an  injury  to  the  nursery  business  to 
agitate  the  subject.  This  has  been  proven  false  by  a 
large  concern  in  Geneva,  who  advertise  that  they 
fumigate  all  their  stock,  and  paste  large  cards  on  their 
boxes,  stating  '  This  stock  has  been  fumigated,''  and 
have  very  largely  increased  their  business  since  they 
adopted  this  process. 

' '  The  San  Jose  scale  is  doubtless  with  us  to  stay, 
but  it  is  our  duty  to  do  all  that  we  possibly  can  to 
keep  it  under  control,  and  in  my  opinion  we  cannot  be 
too  careful  about  it  for  the  interests  of  the  fruit  grow- 
ers and  every  one  else  in  the  state.  The  serious  dam- 
age to  orcharding  from  this  pest  may  be  judged  from  a 
letter  I  have  received  from  a  prominent  fruit-grower  in 
western  New  York  informing  me  that  he  expected  to 
destroy  about  fifteen  acres  of  valuable  bearing  trees 
this  season  because  they  were  ruined  by  San  Jose 
scale." 

Common- sense  view. — The  following  letter  from 
Isaac  C.  Rogers,  of  the  Rogers  Nurseries,  is  a  plain, 
straightforward  statement  of  f acts  :  ' '  Our  f  umigato- 
rium  is  a  room  inside  the  packing-shed.  The  great 
bulk  we  usually  fumigate  in  a  frost-proof  and  air-tight 
room  after  we  are  ready  for  billing  out  in  the  spring; 
then  the  small  lots  dug  from  time  to  time  are  run  into 
the  smaller  room,  with  an  opening  at  the  top  for  the 
escape  of  the  gas  through  the  roof  after  done.  The 
expense  of  fumigating  is  a  small  matter.  The  bother 
is  a  small  matter  compared  with  the  feeling  of  security 
and  the  fact  that  after  the  trees  have  been  through 
that  deadly  stuff  they  go  out  through  the  country 
carrying  no  mischief  and  trouble  making  insects.  The 


ECONOMIC  VALUE  OF  FUMIGATION  249 

extra  expense  of  handling  is  really  a  small  item.  The 
only  way  it  bothers  us  is  sometimes  in  loading  a  car 
there  will  be  a  shipment  to  get  off  that  has  to  have  a 
few  trees  fumigated,  and  then  with  thirty  minutes  out 
of  an  hour  taken  up  with  the  fumigating  one  has  to 
jump  around  pretty  lively  to  make  connections.  But 
the  rush  and  jump  are  only  parts  of  the  nursery  busi- 
ness and  all  in  the  same  line,  so  we  do  not  mind  it. 
On  an  average  it  costs  us  25  to  30  cents  per  thousand 
for  the  actual  fumigation,  including  the  extra  hand- 
ling. 

1 '  We  have  been  fumigating  now  for  three  or  four 
years  and  have  had  no  trouble  from  loss  of  trees  as  yet, 
although  we  were  assured  by  the  antifumigators  that 
we  would  have  our  trees  to  replace.  We  are  careful  to 
fumigate  the  trees  when  dry,  and  for  that  reason  like 
the  fumigating  room  as  a  part  of  the  packing-shed 
much  better  than  to  have  it  as  a  separate  building.  If 
the  trees  come  in  during  a  wet  day  they  can  be  allowed 
to  dry  before  being  put  in  the  fumigator,  and  it  is  far 
more  convenient  to  be  able  to  step  into  the  room  from 
the  packing-shed  during  any  kind  of  weather. 

"  The  objection  generally  made  by  nurserymen  is 
from  the  fact  that  a  very  large  part  of  the  nursery  stock 
grown  in  western  New  York  does  not  go  direct  to 
planters,  but  is  shipped  here  and  there  to  dealers  and 
nurserymen  all  over  the  United  States.  Nurserymen 
in  other  sections  must  have  their  stock  shipped  early  so 
they  can  reship  to  their  customers,  probably  back  in 
New  York.  In  order  to  get  this  done  and  the  trees 
planted  before  it  freezes  up,  they  have  to  be  dug  before 
they  are  fully  matured.  Some  nurserymen  fear  that 


250  FUMIGATION   METHODS 

fumigation  will  injure  them  in  this  condition.  There 
will  be  kicks  along  the  line,  for  frequently  trees  are 
shipped  and  reshipped,  sold  and  resold,  several  times 
before  they  are  eventually  planted,  and  no  doubt  fre- 
quently set  a  few  miles  from  where  they  were  grown. 
At  the  other  end  of  the  season  there  are  always  lots  of 
people  who  forget  all  about  ordering  until  the  trees 
begin  to  grow  or  come  into  bloom,  and  then  it  is  too 
late  to  fumigate  safely  at  the  usual  strength.  These 
two  extremes  seem  to  block  the  way  and  prejudice 
many  nurserymen  against  fumigation. 

* '  We  do  not  have  to  depend  upon  the  notions  of 
other  nurserymen  hundreds  of  miles  away.  We  can 
dig,  fumigate,  and  pack  our  trees  when  the  right  time 
comes.  This  accounts,  in  part,  for  our  not  being  *  in 
the  ring,'  as  it  were,  fighting  our  own  interests,  as  some 
nurserymen  have  been  doing.  In  some  cases  with  a 
large  majority  of  tree  growers  in  New  York  there  is 
really  no  connection  or  kindred  interest  between  them 
and  the  fruit  grower.  Their  product  is  frequently  sold 
before  digging-time,  to  go  in  car-load  lots  to  other 
nurseries  hundreds  of  miles  out  of  New  York,  and  little 
or  nothing  do  they  care  what  becomes  of  the  trees  after- 
ward or  whether  they  are  planted  in  New  York  or  in 
South  Africa." 

Protects  customers. — We  are  thoroughly  convinced 
that  fumigation  is  most  necessary  in  order  that  the 
grower  of  nursery  stock  may  supply  his  customers 
with  trees  and  vines  absolutely  free  from  all  insect  life. 
While  most  nursery  stock  grown  in  this  section  is  not 
infested  with  San  Jose  scale,  yet  all  is  more  or  less 
infested  with  aphis  and  other  troublesome  forms  of 


ECONOMIC   VALUE   OF   FUMIGATION  251 

insect  life,  that  can  but  be  deleterious  to  the  tree  if 
allowed  to  remain  thereon  in  an  active  condition.  For 
the  past  two  years  we  have  fumigated  everything  that 
we  have  sent  out  except  evergeens,  and  so  far  have 
never  detected  any  injurious  effects. — THE  R.  G. 
CHASE  COMPANY,  Nurseries,  New  York. 

Utah. — We  believe  this  is  the  most  efficient  treat- 
ment that  nursery  stock  can  be  given.  If  the  build- 
ing is  air-tight  and  the  chemicals  are  mixed  in  the 
proper  proportion,  it  is  undoubtedly  destructive  to  all 
kinds  of  insects  and  no  harm  results  to  the  stock. 
After  putting  gas  into  the  building  we  leave  our  stock 
stand  from  one-half  to  three-fourths  of  an  hour,  then 
throw  the  double  doors  wide  open,  and  allow  the 
building  to  ventilate  from  fifteen  to  twenty-five  min- 
utes before  attempting  to  remove  the  stock.  We 
believe  it  pays  us  to  run  all  nursery  stock  through  our 
cyanide  house.  We  have  treated  from  two  to  three 
hundred  thousand  trees  annually  for  the  past  three 
years.  In  1901  we  expect  to  treat  half  a  million.  If 
one  had  more  stock  than  this  it  would  be  advisable  to 
build  a  larger  house.  We  think  it  quite  necessary  to 
have  the  roots  of  the  trees  comparatively  clean.  If 
they  are  covered  with  dirt,  especially  clay  soil,  the  gas 
may  not  penetrate  to  the  insects,  especially  woolly 
aphis.  Do  not  think  our  building  cost  to  exceed  $50. 
—VAN  METER,  HARNESS  &  Co.,  Proprietors  Davis 
County  Nurseries,  Utah. 

Utah. — I  have  followed  your  directions  for  fumi- 
gating, which  have  proven  very  satisfactory.  I  have 
had  no  opportunity  for  experimenting  with  scale,  but 


252  FUMIGATION  METHODS 

find  the  gas  a  sure  remedy  for  woolly  aphis  and  other 
insects. — D.  M.  MOORE,  Moore's  Nurseries,  Utah. 

Opinions  of  orchardists  on  fumigation  in  New  South 
Wales. — Bevan  Brothers,  of  Galston,  write  W.  J. 
Allen,  the  government  expert,  as  follows:  "  We  have 
fumigated  some  1,500  trees  since  this  time  (July)  last 
year,  and  the  results  have  been  very  satisfactory. 
Without  doubt  nearly  every  scale  has  been  killed,  the 
trees  are  healthy,  and  the  fruit  clean.  We  formerly 
sprayed  from  three  to  four  times  a  year,  tried  several 
preparations,  and  never  got  thorough  satisfaction  out 
of  any.  Occasionally  patches  of  live  scale  do  remain 
on  trees  that  have  been  fumigated,  but,  as  far  as  we 
can  judge,  this  has  only  happened  where  fruit  with 
scale  on  it  has  pressed  against  the  side  of  the  tent,  or 
where  the  dose  of  acid  has  not  been  quite  sufficient  to 
poison  the  scale  on  the  lower  limbs. 

1 '  Several  of  our  neighbors  having  seen  the  results 
on  our  trees  have  had  tents  made,  and  set  to  work 
cyaniding.  This  is  surely  the  best  proof  of  its  value. 
You  are  aware  that  we  use  a  cheap  tent  made  of  calico, 
costing  wholesale  about  is.  $d.  per  yard,  double  width. 
So  far  this  has  answered  admirably.  Tents  10  feet  in 
diameter  by  12  high  cost  from  305.  to  355.  This  re- 
duction in  the  cost  of  the  tent  really  made  fumigation 
possible  to  us.  We  have  had  to  thank  your  depart- 
ment for  many  things,  but  for  none  are  our  thanks 
more  deserved  than  for  teaching  us  cyaniding. ' ' 

R.  If.  Sheppard,  Wesbank,  Emu  Plains,  says  in 
same  report :  "I  was  prompted  to  enter  upon  what 
seemed  at  first  rather  an  arduous  undertaking,  viz., 
the  fumigation  of  my  citrus  trees  for  the  destruction  of 


ECONOMIC   VAIJJK  OF  FUMIGATION  253 

scale,  by  a  practical  demonstration  given  by  W.  J. 
Allen,  government  fruit  expert,  who  at  the  same  time 
placed  at  my  disposal  a  large  amount  of  useful  infor- 
mation for  my  guidance  at  the  start.  The  first  diffi- 
culty which  presented  itself  was  that  of  procuring 
tents — how  many  to  get,  what  sizes,  and  where  to  get 
them  at  a  reasonable  cost.  Firms  in  Sydney  asked  a 
price  that  was  practically  prohibitory.  In  my  diffi- 
culty I  applied  to  Mr.  Walter  Bevan,  of  Galston,  who 
at  this  time  was  having  his  trees  treated  by  this  pro- 
cess, and  he  it  was  who  put  me  in  the  way  of  getting 
them  at  a  moderate  figure.  The  least  expensive 
method  is  to  buy  the  material  at  some  wholesale  house 
and  have  it  made  up  at  home.  For  the  purpose  noth- 
ing could  be  better  than  '  circus- tent  calico, '  both  for 
lightness  and  durability.  At  present  the  wholesale 
price  is  is.  $/4d.  per  yard  of  6  feet  wide. 

' '  In  my  opinion  no  grower  should  bother  with 
tents,  but  have  the  material  made  into  square  sheets 
the  sizes  he  requires.  They  are  easier  to  make  than 
tents,  answer  the  same  purpose  exactly,  and  are  much 
more  readily  placed  over  the  trees.  The  number  to 
get  and  the  sizes  will  naturally  depend  on  the  trees 
the  grower  has.  I  got  four  tents  and  two  sheets,  each 
sheet  being  40  x  40  feet,  and  with  this  number  two 
men  can  do  from  30  to  50  trees  each  day.  I  began 
fumigating  about  the  end  of  January  last,  and  instead 
of  doing  the  work  at  night,  which  is  generally  accepted 
as  the  proper  time,  I  did  all  mine  by  daylight.  Orange 
trees  badly  infested  with  scale,  I  found,  lost  a  large 
portion  of  their  leaves,  those  with  less  scale  a  much 
smaller  quantity.  Having  the  cyanide  broken  up  too 


254  FUMIGATION  METHODS 

finely,  and  thus  causing  the  gas  to  generate  very  quickly, 
seemed  to  tend  to  defoliation  as  much  as  anything. 
However,  a  very  strong,  new  growth  started,  and  the 
trees  soon  assumed  a  splendid  appearance.  Curiously 
enough,  lemon  and  mandarin  trees,  though  treated  in 
the  very  hottest  days,  lost  no  leaves  at  all.  Fumiga- 
tion, no  doubt,  is  the  only  royal  road  to  clean  trees — 
it  absolutely  blots  the  red  scale  out,  and  if  done  before 
the  fruit  is  too  large,  a  clean  crop  is  assured,  as  the 
expansion  of  the  fruit  causes  the  scale  to  drop  off. 
Brown  olive  scale  is  decimated,  but  not  always  alto- 
gether destroyed,  though  it  looks  as  if,  of  the  two,  it 
would  be  easier  to  kill.  So  far  I  have  treated  1,800 
trees  of  various  sizes,  and  I  am  sure  growers  will  be 
pleased  to  know  that  the  average  cost  per  tree,  includ- 
ing labor,  price  of  tents,  chemicals,  etc.,  only  amounts 
to  T%d.  Thus  for  *]d  you  get  a  healthy  tree  and  clean 
fruit.  How  much  more  is  this  worth  than  a  sickly 
tree  and  unmarketable  fruit?  To  show  how  fumiga- 
tion is  regarded  on  Emu  Plains,  I  can  inform  those  who 
are  in  doubt  that  since  my  neighbor  growers  witnessed 
the  effect  of  the  treatment  here  some  have  already  com- 
menced, and  others  contemplate  doing  so." 

M.  Brown,  of  Messrs.  Rodgers  &  Co.,  Galston, 
writes  Mr.  Allen  as  follows:  "We  have  fumigated 
this  year  some  i ,  800  trees,  and  are  entirely  satisfied 
with  the  result.  We  started  fumigating  the  first  week 
in  May,  and  a  live  scale  cannot  be  found  on  any  of  the 
trees  done.  Fully  50  per  cent,  of  the  scale  have  been 
cleaned  off  the  trees,  and  I  hope  to  see  the  greater  part 
of  the  remainder  cleared  off  before  the  bulk  of  the 
fruit  is  marketed.  Of  course,  you  will  understand 


ECONOMIC  VALUE  OF  FUMIGATION  255 

that  May  is  too  late  to  commence  fumigating  to  obtain 
the  best  result,  but  we  could  not  start  earlier,  and 
next  year  I  intend  to  start  early  in  February,  so  that 
the  oranges,  while  still  growing,  will  throw  off  the 
dead  scale.  My  reason  for  starting  in  February  is  that 
I  have  done  some  experimenting,  and  have  closely 
watched  the  result,  and  feel  sure  that  citrus  trees  done 
in  that  month  will  be  almost  absolutely  clean  by  May. 
I  did  some  twelve  or  fourteen  of  the  worst  trees  I 
could  find  in  the  orchard  fourteen  months  ago  with  the 
government  tents  which  you  lent  me,  and  at  the  pres- 
ent time  they  are  almost  perfectly  clean  ;  what  little 
scale  there  is  on  them  has  only  come  in  the  last  two 
months. 

' '  As  you  know,  I  have  had  some  experience  with 
spraying,  and  have  tried  practically  every  known 
spray,  and  also  had  Mr.  Chomley  up  here  experiment- 
ing with  different  sprays,  and  I  have  no  hesitation  in 
saying  that  spraying  is  a  thing  of  the  past,  and  quite 
out  of  date  compared  with  fumigation,  as  the  fumiga- 
tion gives  a  ten  times  better  result,  and  is  not  nearly 
so  costly,  once  you  buy  the  tents,  and  these  are  not 
very  expensive.  I  bought  strong  unbleached  calico, 
double  width,  wholesale,  at  is.  2d.  per  yard,  and  find 
this  will  hold  the  fumes  as  well  as  canvas,  if  it  is  not 
blowing  a  strong  wind.  I  got  200  yards,  which  made 
nine  tents  of  various  sizes  (but  all  of  them  are  a  good 
size),  and  cut  the  stuff  out  myself  in  the  following 
manner  :  Cut  out  a  circle  6  feet  in  diameter,  then  one 
length  of  calico  30  feet  long,  and  sew  round  the  circle  ; 
then  cut  out  another  length  30  feet  long,  and  join  on 
the  other  piece  and  sew  up  the  seam  ;  this  will  give 


256  FUMIGATION   METHODS 

you  a  tent  which  will  cover  a  well-grown  ten-year-old 
orange  tree,  provided  the  tree  is  not  more  than  13  feet 
high. 

( '  What  I  should  like  to  see  the  government  do  is 
to  get  together  a  large  plant  (say,  twenty-five  tents) 
and  employ  four  men  to  manage  it,  and  go  round  to 
various  orchards  in  each  district  and  fumigate  them, 
charging  the  owner  the  cost  of  cyanide,  etc.,  labor, 
and  enough  to  allow  for  wear  and  tear  in  tents,  and 
interest  on  their  outlay  for  same,  as  I  feel  sure  many 
orchard  owners  would  be  only  too  glad  to  have  their 
orchards  done,  but  they  have  not  the  capital  to  spare 
to  get  the  necessary  plant,  as  one  wants  a  fair  num- 
ber of  tents  to  do  the  work  quickly.  I  find  myself 
and  one  man  can  manage  fourteen  tents  comfortably. 
Your  formula  of  one  cyanide,  one  acid,  and  three  water 
is  not  sufficient  to  work  off  the  cyanide  in  forty-five 
minutes,  so  I  use  one,  one-and-a-half  of  acid,  and 
three.  You  are  welcome  to  publish  all  of  this  if  you 
think  it  of  any  use,  and  to  say  that  I  strongly  urge 
growers  to  go  in  for  fumigating,  as  there  is  nothing  else 
to  compare  with  it  in  efficiency  and  cheapness. ' ' 


CHAPTER  XXI 
FUMIGATION  WITH   CARBON  BISULPHID 

T"!HE  fact  that  carbon  bisulphid  volatilizes  readily, 
has  fumes  heavier  than  air,  creates  an  atmos- 
phere in -which  no  animal  life  can  exist,  and 
can  be  used  without  injury  to  edible  materials, 
all  combine  to  make  it  one  of  the  very  best  substances 
for  the  destruction  of  certain  subterranean  insects  and 
other  undesirable  animals.  For  killing  insect  pests  in 
stored  grains  and  other  materials  in  bulk  it  has  no 
superior.  Its  vapor  will  penetrate  to  the  lowermost 
cracks  and  crevices  in  a  granery,  carrying  the  death- 
dealing  atmosphere  with  it.  It  can  be  used  economic- 
ally where  hydrocyanic  acid  gas  cannot  be  employed 
on  account  of  its  heavy  vapor. 

First  use  of  carbon  bisulphid  to  destroy  inseEls. — 
During  1856  and  1857  M.  Doyere  used  carbon  bisul- 
phid as  an  insecticide.  He  demonstrated  that  it  could 
be  used  to  destroy  weevils  and  other  pests  in  corn  and 
barley  without  injuring  the  grain  either  for  planting 
or  edible  purposes.  Since  that  time  it  has  been  used 
for  combatting  various  insect  pests.  At  first  the  cost 
of  carbon  bisulphid  precluded  its  general  use  as  an 
insecticide  on  a  very  extensive  scale.  Largely  through 
the  efforts  and  inventive  genius  of  Kdward  R.  Taylor, 
a  manufacturing  chemist,  a  grade  known  as  "  Fuma 
carbon  bisulphid  ' '  was  placed  upon  the  market  a  few 
years  ago.  It  is  now  the  standard  for  insecticide  pur- 

257 


258  FUMIGATION   METHODS 

poses  and  is  sold  at  a  $>rice  within  reach  of  those  who 
desire  to  use  if  for  economic  purposes. 

Chemical  properties. — Carbon  bisulphid  is  a  color- 
less liquid  resembling  water.  It  is  formed  by  the 
union  of  two  elementary  particles  of  sulphur  with  one 
of  carbon  (charcoal) ;  thus  the  chemical  symbol  CS2. 
It  is  made  on  a  large  scale  by  a  new  electric  process 
invented  and  patented  by  Edward  R.  Taylor.  The 
fumes  of  burning  sulphur  are  passed  over  red-hot 
charcoal  and  the  resulting  vapors  are  condensed  to  a 
liquid  by  cooling.  Mr.  Taylor's  new  plant  at  Pen  Yan, 
New  York,  has  a  daily  capacity  of  20,000  pounds  at 
present.  The  liquid  is  one-fourth  heavier  than  water. 
Its  specific  gravity  is  1.29  at  the  freezing  temperature 
of  water.  It  is  very  refractive,  reflecting  light  much 
more  readily  than  water  when  its  surface  is  disturbed. 
It  is  extremely  volatile  and  evaporation  is  rapid  when 
the  surface  is  exposed  to  the  air.  The  temperature  of 
the  liquid  and  the  air,  as  well  as  the  evaporating  sur- 
face, determines  the  rapidity  of  evaporation.  By  cov- 
ering the  surface  of  carbon  bisulphid  with  water, 
which  is  lighter,  evaporation  can  be  prevented. 

Carbon  bisulphid  is  not  necessarily  dangerous  to 
the  skin,  but  when  the  fingers  or  hands  are  frequently 
moistened  with  it  the  skin  becomes  rather  dry  and 
harsh  and  liable  to  crack  or  chafe.  On  account  of  its 
volatility  it  absorbs  considerable  heat.  Perfectly  pure 
carbon  bisulphid  has  an  acrid  taste  and  a  rather 
sweetish,  not  disagreeable,  etherial  odor,  similar  indeed 
to  that  of  ether  or  chloroform.  Pure  carbon  bisulphid 
will  not  injure  or  stain  the  finest  garments  or  fabrics. 
It  can  be  poured  directly  upon  food  stuffs  without  im- 


FUMIGATION   WITH    CARBON   BISULPHID          259 

pairing  their  edibility.  All  trace  of  the  odor  dis- 
appears quickly  when  such  produces  are  exposed  to 
the  air.  The  ordinary  commercial  article  has  a  slightly 
yellowish  tinge  due  to  its  impurities,  which  also  give 
it  a  rank  fetid  odor  that  is  extremely  obnoxious. 
When  an  impure  article  is  used,  a  slight  residue  may 
be  left  after  the  evaporation  of  the  liquid.  Such  a 
grade  will  stain  fabrics,  and  it  should  be  poured  upon 
food  stuffs  with  care,  though  its  vapor  will  do  no  harm. 
Liquid  carbon  bisulphid  is  not  explosive,  and  there 
need  be  no  fear  of  handling  it,  provided  the  vessels  are 
perfectly  tight.  It  should  be  kept  where  there  is  no 
fire  in  a  dry  place,  so  the  cans  will  not  rust.  Carbon 
bisulphid  boils  at  115°  F.  One  volume  of  the  liquid 
is  said  to  give  375  volumes  of  vapor  upon  evaporation. 

Properties  of  vapor. — Owing  to  its  heavy  properties 
the  vapor  of  carbon  bisulphid  can  be  poured  from  one 
vessel  to  another,  like  water.  It  is  2.63  times  heavier 
than  air.  It  diffuses  quite  readily  through  the  air,  as 
can  be  perceived  by  its  odor.  It  has  a  tendency  to 
seek  lower  levels,  and  consequently  will  be  more  dense 
as  it  works  downward.  This  fact  should  be  borne  in 
mind,  as  it  has  an  important  bearing  upon  the  applica- 
tion of  this  material.  It  is  the  opposite  of  hydrocyanic 
acid  gas,  which  is  lighter  than  air.  Carbon  bisulphid 
in  both  liquid  and  vapor  form  is  an  efficient  disinfectant. 
Meats  have  been  kept  in  its  atmosphere  for  many  weeks. 
The  disinfectant  is  the  same  gas  as  is  formed  by  burn- 
ing sulphur  or  brimstone. 

Inhaling  the  gas. — The  extreme  effects  of  the  vapor 
of  carbon  bisulphid  if  inhaled  are  giddiness,  vomiting, 
congestion,  coma,  and  death.  The  material  can  be 


260  FUMIGATION   METHODS 

used  in  mills,  warehouses,  and  other  enclosures  with 
perfect  safety.  A  reasonable  amount  of  the  vapor  can 
be  inhaled,  while  the  liquid  is  being  distributed  in  a 
building  without  injury  to  the  operator.  From  per- 
sonal experience  in  making  many  practical  applications 
of  carbon  bisulphid  in  buildings,  the  writer  has  never 
experienced  any  ill  feeling  or  bad  after-effects  from 
the  gas.  The  sense  of  smell  is  the  first  affected.  If 
one  is  confined  in  a  room  where  the  gas  is  being  gen- 
erated, for  a  short  time  the  olfactory  organs  are 
benumbed  or  deadened.  As  the  oxygen  in  the  lungs 
becomes  exhausted,  the  heart-throbs  become  more 
rapid.  The  mind  becomes  sluggish,  while  hearing  and 
sight  are  weakened.  This  is  usually  followed  by  dizzi- 
ness. The  sensation  is  not  disagreeable,  and  a  person 
has  no  immediate  desire  to  get  out  of  the  gas.  A 
person  in  this  condition  should  leave  the  building  being 
fumigated  at  once  and  freely  inhale  fresh  air. 

Mr.  W.  E.  Hinds,  who  has  had  some  experience 
with  the  practical  application  of  this  gas,  in  a  recent 
Farmers'  Bulletin  (No.  145)  by  the  United  States  De- 
partment of  Agriculture,  says  :  ' l  Owing  to  the  effect 
of  the  gas  upon  the  heart  action,  it  may  be  well  to 
caution  persons  having  any  trouble  or  weakness  about 
the  heart  against  taking  any  extended  part  in  the 
application  of  the  bisulphid.  It  should  be  clearly 
understood  by  those  who  use  it  that  the  action  of  the 
gas  is  somewhat  poisoning  as  well  as  suffocating. 
Should  the  operator  persist  in  remaining  in  the  room 
after  the  dizziness  comes  on,  he  will  be  in  danger  of 
falling,  and,  if  not  discovered,  he  will  soon  suffocate. 
Even  if  he  should  get  out  safely,  the  ill  effects  will  be 


FUMIGATION  WITH   CARBON   BISULPHID          26 1 

more  marked  and  a  severe  headache,  at  least,  might 
ensue.  If  upon  the  approach  of  dizziness,  the  operator 
goes  at  once  to  a  window,  or  better  still  out  of  doors, 
an  abundance  of  fresh  air  will  in  a  few  minutes  remove 
all  ill  effects,  and  no  injury  will  result  from  the  experi- 
ence. The  inhalation  of  the  fumes  can  be  somewhat 
retarded  by  tying  a  wet  handkerchief  tightly  over  the 
face.  This,  however,  merely  diminishes  the  amount  of 
air  taken  into  the  lungs  without  affecting  the  propor- 
tion of  vapor  contained  therein. ' ' 

When  obliged  to  enter  a  room  in  which  the  air  is 
charged  with  any  considerable  amount  of  vapor,  Mr. 
Hinds  makes  use  of  the  following  simple  device,  which 
is  perfectly  effectual :  A  large  paper  bag  holding  20 
quarts  or  more  is  tied  tightly  around  a  short  piece  of 
tubing  of  glass,  rubber,  or  metal.  When  inflated, 
the  bag  contains  sufficient  air  to  enable  one  to  respire 
into  it  for  several  minutes  without  discomfort.  Being 
very  light,  it  can  be  carried  by  the  tube  in  the  mouth, 
thus  leaving  the  hands  free  for  any  work  desired. 
Carbon  bisulphid  can  be  handled  with  much  greater 
safety  and  far  less  fear  than  is  possible  where  the  user 
knows  there  is  danger  but  does  not  know  just  what  the 
danger  is.  The  danger  from  its  use  is  practically  of 
the  same  kind  as  that  from  gasoline,  which  is  in  com- 
mon daily  use.  The  danger  is  very  much  less,  how- 
ever, since  every  precaution  is  taken  to  keep  carbon 
bisulphid  from  the  proximity  of  fire,  while  gasoline  is 
used  principally  in  connection  with  it. 

Commercial  uses. — Although  the  insecticide  proper- 
ties of  carbon  bisulphid  were  discovered  by  Doyere  in 
1856,  and  tested  three  years  later  by  Baron  Paul  The- 


262  FUMIGATION   METHODS 

nard,  it  remained  for  M.  Cornu  and  M.  Mouillefert,  two 
French  investigators,  to  determine  its  real  value  in 
this  connection  nearly  twenty  years  later.  They  ex- 
perimented upon  many  species  of  insects  representing 
various  groups,  paying  particular  attention  to  the 
grape  phylloxera,  the  most  serious  pest  to  the  vine- 
yards of  France.  They  found  that  an  atmosphere 
containing  one  part  of  carbon  bisulphid  and  nine  parts 
of  air  killed  insects  within  a  few  seconds  when  con- 
fined in  the  vapor  ;  and  that  one  part  in  254  parts  of 
air  was  also  fatal  in  about  one  and  one-quarter  hours. 

The  application  of  carbon  bisulphid  for  the  de- 
struction of  insects  in  mills,  elevators,  and  other  places 
where  large  quantities  of  grain  is  stored  is  of  recent 
origin.  Its  extensive  use  to  kill  gophers,  ground 
squirrels,  and  other  noxious  subterranean  and  undesir- 
able rodents  is  a  comparatively  new  method. 

In  the  arts  it  is  employed  as  a  solvent  of  sulphur, 
phosphorous,  oils,  resins,  caoutchouc,  gutta-percha, 
etc.  It  is  indispensable  in  the  manufacture  of  rubber 
and  waterproof  goods.  In  the  manufacture  of  woolen 
goods  it  is  used  to  abstract  oils  and  fats  from  the  wool. 
It  is  not  considered  an  extra  hazardous  material, 
otherwise  it  wrould  not  be  so  extensively  used. 

Work  in  France  against  Phylloxera. — The  treatment 
of  vines  in  France  with  carbon  bisulphid  for  the 
destruction  of  phylloxera  is  very  extensive.  Some 
years  more  than  a  quarter  of  a  million  acres  receive 
treatment.  Upon  being  introduced  into  the  soil  at  some 
depth  below  the  surface  the  liquid  evaporates  as  it 
does  in  the  open  air,  but  much  more  slowly.  The 
vapor  diffuses  through  the  air  spaces  of  the  soil.  It 


FUMIGATION   WITH    CARBON    BISULPHID          263 

produces  an  atmosphere  fatal  to  all  insects  within  its 
reach.  The  rapidity  of  evaporation,  extent  of  dif- 
fusion, and  persistence  of  the  vapor  in  the  soil  vary 
widely  in  different  soils.  It  evaporates  most  rapidly 
in  a  warm,  dry,  sandy  soil.  The  persistence  of  the 
vapor  is  also  shortest  in  such  a  soil,  and  it  diffuses  so 
rapidly  most  insects  will  survive  an  ordinary  dose. 
The  treatment  cannot  be  successfully  applied  on  such 
a  soil  in  its  dry  condition.  On  the  other  hand,  diffu- 
sion is  slowest  in  heavy,  wet,  clay  soil;  and  when  such 
soil  is  saturated  with  water  it  is  almost  entirely  pre- 
vented. Moisture  lowers  the  temperature  and  de- 
creases the  permeability  of  the  soil ;  it  also  prevents 
the  evaporation  of  the  liquid,  and  thus  retards  diffu- 
sion. Between  these  two  extremes  there  is  a  medium 
condition  of  moisture  which  is  most  favorable  for  treat- 
ment. 

Action  in  different  soils . — Sandy  soils  permit  an  even 
but  too  rapid  diffusion  of  the  vapor.  Rocky  soils  are 
not  of  even  texture,  and  naturally  the  vapors  follow 
the  lines  of  least  resistance.  Heavy  clay  soils,  when 
very  dry,  are  usually  much  broken  by  cracks  and 
fissures,  which  may  run  from  the  surface  to  a  consider- 
able depth.  Through  such  fissures  the  vapor  escapes 
rapidly  without  permeating  the  soil  to  any  extent,  and 
its  insecticidal  value  is  therefore  slight.  But  when 
such  a  soil  is  well  moistened  it  is  even  in  texture  and 
very  favorable  to  treatment.  The  depth  of  the  soil  is 
an  important  factor  in  determining  how  much  carbon 
bisulphid  must  be  used  for  a  given  area.  If  the  soil  is 
shallow  and  the  subsoil  very  dense  and  impervious,  it 
is  evident  that  much  less  liquid  will  be  required  to 


264  FUMIGATION   METHODS 

produce  a  death  atmosphere  than  will  be  needed  in  a 
soil  of  much  greater  depth.  In  soils  of  the  same 
character  and  condition  the  amount  needed  will  be 
proportional  to  the  permeable  depth  of  the  soil.  In 
heavy,  compact  soils  increase  the  number  of  injections 
and  diminish  the  dose;  in  light,  deep,  permeable  soils 
decrease  the  number  of  holes  and  increase  the  dose. 

In  field  experiments  with  the  grape,  using  plain 
carbon  bisulphid  in  quite  fresh  soil,  vines  withstood 
105  c.  c.  of  carbon  bisulphid,  nearly  4.4  ounces, 
divided  equally  among  three  holes  placed  about  16 
inches  from  the  base  of  the  vine  and  at  a  depth  of  about 
20  inches;  but  180  c.  c. ,  7^  ounces,  proved  fatal  to 
the  vines.  In  warmer,  drier,  more  shallow  soil  a  dose 
of  90  c.  c.  per  vine,  similarly  placed,  proved  fatal. 
After  considerable  rain,  when  the  ground  was  quite 
wet,  a  vine  withstood  260  c.  c.  of  carbon  bisulphid, 
and  some  vines  are  said  to  have  withstood  400  c.  c. 
The  treatment  should  never  be  applied  for  some  time 
after  plowing  or  cultivating,  as  a  firm,  compact,  moist 
surface  is  much  more  favorable  to  the  retention  of  the 
vapor.  For  the  same  reason  about  fifteen  days  should 
be  allowed  after  treatment  before  cultivation  is  re- 
sumed. If  the  soil  is  either  very  wet  or  dry,  treatment 
should  be  withheld.  To  be  in  the  most  favorable  con- 
dition for  treatment,  the  soil  should  be  quite  moist  and 
moderately  permeable,  with  a  firm,  even  surface,  well 
compacted  by  rain  and  having  a  depth  of  at  least  eight 
inches. 

The  extent  of  diffusion  of  the  vapor  determines  the 
distance  apart  at  which  the  injections  must  be  made  to 
reach  all  parts  of 'the  soil  evenly  and  effectively.  This 


FUMIGATION   WITH    CARBON    BISULPHID  265 

varies  considerably  with  the  amount  of  the  dose,  the 
temperature  and  humidity  of  the  soil,  and  other  con- 
ditions. It  has  been  found  more  satisfactory  to  employ 
smaller  and  more  frequent  doses  rather  than  a  few 
large  ones.  A  dose  of  5  or  6  grammes,  */6  to  '/4  ounce, 
is  believed  to  be  thoroughly  effective  through  a  radius 
of  from  1 2  to  20  inches,  though  it  may  penetrate  much 
farther  than  that.  The  general  rule  is  to  make  three 
injections  per  square  meter,  nearly  i'/6  square  yards, 
in  light  soils,  and  four  injections  in  heavy  soil.  The 
holes  should  be  at  regular  intervals,  so  as  to  cover  the 
ground  evenly,  and  never  nearer  than  one  foot  to  the 
base  of  the  vine.  To  be  effective  all  the  ground  must 
be  treated. 

On  account  of  the  liability  of  injuring  the  vines  it 
has  been  found  best  to  make  the  treatment  in  two  small 
applications,  separated  by  an  interval  of  from  six  to  ten 
days.  This  decreases  the  density  of  the  vapor,  but 
continues  its  action  for  a  much  longer  time.  It 
removes  the  danger  of  injuring  the  vines,  and  gives 
even  better  results  upon  the  insects  than  would  be 
obtained  by  one  large  dose.  The  total  amount  of  car- 
bon bisulphid  to  be  used  should  be  divided  into  as 
many  equal  parts  as  there  are  injections  to  be  made. 
The  holes  for  the  second  treatment  should  be  inter- 
mediate between  those  for  the  first.  The  depth  of  the 
holes  will  depend  somewhat  upon  the  depth  and  per- 
meability of  the  soil.  The  average  depth  is  about  one 
foot.  Holes  1 6  inches  deep  are  desirable  on  very 
permeable  soil. 

Treatment  may  be  applied  at  any  season  of  the  year; 
but,  as  it  is  followed  by  a  slight  check  in  growth,  it 


266  FUMIGATION   METHODS 

should  not  be  applied  either  at  the  flowering  or  fruit- 
ing season,  as  the  check  would  injure  the  crop  most  at 
those  seasons.  The  injury  to  the  vines  results'  from 
the  killing  of  the  tender,  fibrous,  feeding  roots.  It 
would  therefore  be  better  to  apply  the  treatment  before 
these  roots  have  started  in  early  spring,  or  after  they 
have  become  hardened  in  the  fall.  The  condition  of 
the  soil  usually  favors  the  spring  treatment,  and  the 
condition  of  the  insect  is  said  to  make  it  more  suscep- 
tible at  that  time. 

Amount  to  use  per  acre. — To  secure  extinction  it  is 
usual  to  apply  about  300  grammes,  nearly  10  ounces, 
per  vine,  using  150  grammes  in  each  of  two  applica- 
tions ten  or  twelve  days  apart.  This  will  kill  ninety- 
nine  out  of  every  hundred  vines.  In  cultural  treat- 
ment the  amount  of  the  liquid  to  be  used  varies  from 
140  to  265  pounds  per  acre. 

Instruments  for  application. — One  of  the  principal 
difficulties  in  the  first  use  of  carbon  bisulphid  was  to 
force  the  vapors  to  the  desired  depth.  When  first 
used  below  the  surface  it  was  poured  into  holes  formed 
by  driving  an  iron  bar  with  a  maul.  The  demand  for 
a  more  convenient,  accurate,  and  rapid  working  in- 
strument was  soon  met  by  the  invention  of  the  pal- 
injector  by  M.  Gastine.  This  instrument  was  later 
improved  by  M.  Vermorel.  The  carbon  bisulphid  is 
placed  in  a  large  chamber,  from  which  an  outlet  leads 
down  through  a  series  of  valves,  so  adjusted  that  the 
amount  of  each  discharge  can  be  exactly  regulated  as 
desired,  and  opens  near  the  tip  of  the  pointed  bar. 
The  instrument  is  forced  into  the  ground  by  the 
handle  and  the  pressure  of  the  foot  upon  the  spur  to  a 


FUMIGATION  WITH   CARBON   BISULPHID          267 

depth  of  about  one  foot  ;  the  central  plunger  is  then 
pressed  down  and  the  desired  amount  of  the  liquid  is 
discharged  ;  the  instrument  is  withdrawn,  and  the  hole 
closed  with  the  foot,  or,  as  is  usual  in  extensive  work, 
another  workman  follows  with  a  rammer,  with  which 
the  holes  are  closed,  and  the  soil  at  the  same  time  is 
firmly  compacted.  It  is  said  that  two  men  working 
together  in  this  way  can  make  between  2,000  and  3,000 
injections  per  day.  One  acre  will  require  on  the  aver- 
age from  10,000  to  12,000  holes.  Plows  have  also 
been  devised  for  injecting  carbon  bisulphid  into  the 
the  soil,  but  they  are  not  altogether  satisfactory.  The 
same  methods  can  be  applied  to  other  subterranean 
insects  and  underground  creatures. 

Root-maggots  and  root-worms. — Both  the  larvae  and 
pupae  of  the  cabbage  root-maggot  are  destroyed  with 
carbon  bisulphid.  Prof.  M.  V.  Slingerland,  of  Cor- 
nell University,  has  determined  these  points  with 
accuracy,  giving  the  details  of  his  experiments  in  bul- 
letin form.  (Bulletin  No.  78,  Cornell  University  Ex- 
periment Station. )  Where  used  for  the  root-maggot 
the  hole  should  start  3  or  4  inches  from  the  stem  of 
the  plant  and  run  down  obliquely  a  little  below  the 
roots,  where  the  liquid  is  deposited.  The  dose  re- 
quired varies  from  a  teaspoonful  for  each  small  plant 
to  a  tablespoonful  for  large  plants,  an  equivalent  of 
about  one-quarter  of  an  ounce  in  the  former  case  and 
one  ounce  in  the  latter.  One  injection  will  be  sufficient 
if  made  in  time.  The  conditions  of  the  soil  noted 
under  phylloxera  treatment  will  have  practically  the 
same  influence  in  this  case. 

A  similar   method   of  treatment   will   be  equally 


268  FUMIGATION   METHODS 

effective  against  the  -grape  root- worm,  Fidia  vitidda. 
To  facilitate  the  application  of -carbon  bisulphid  the 
McGowen  injector  was  invented.  It  is  a  very  con- 
venient instrument,  and  can  be  adapted  to  nearly  all 
uses  of  carbon  bisulphid  for  underground  insects. 

Destroying  ants  in  lawns  and  other  places. — Usually 
by  careful  observation  the  common  ants,  excepting, 
perhaps,  the  little  red  ants  frequenting  houses,  can  be 
traced  to  their  outside  homes.  The  treatment  consists 
in  making  one  or  more  holes  in  the  nest  with  a  stick 
or  iron  bar,  one  to  two  feet  deep,  and  pouring  into  each 
hole  a  couple  of  ounces  of  carbon  bisulphid.  The  hole 
should  be  closed  immediately.  The  vapor  may  be 
exploded  at  the  mouth  of  the  hole  with  a  match,  in 
order  to  drive  the  fumes  deeper  into  the  chambers.  If 
the  latter  method  is  adopted,  the  hole  should  be 
covered  with  fresh  earth  immediately  after  the  explo- 
sion, so  as  to  put  out  the  fire  and  retain  the  fumes. 
Otherwise  a  large  portion  of  the  gas  will  be  burned 
and  the  efficiency  of  the  treatment  considerably 
lessened.  After  the  explosion  the  vapor  burns  with  a 
colorless,  invisible  flame.  Carefully  observe  this  point 
before  an  attempt  to  recharge  a  nest  is  made.  Other- 
wise an  explosion  might  follow,  with  serious  results  to 
the  operator.  If  a  large  area  is  infested  the  holes 
should  be  about  one  and  one-half  feet  apart  each  way. 
After  the  carbon  bisulphid  has  been  applied  the  ground 
should  be  thoroughly  watered  to  prevent  too  rapid 
diffusion  of  the  fumes. 

White  grubs  and  mole  crickets,  sometimes  found  in 
lawns  and  gardens,  can  be  treated  in  the  manner  de- 


FUMIGATION  WITH   CARBON  BISULPHID          269 

scribed  for  ants.  One  ounce  per  square  yard  divided 
between  three  or  four  injections  will  be  satisfactory. 
The  most  favorable  time  for  treating  the  grubs  is  after 
they  descend  in  the  ground  in  the  fall  and  before  they 
come  up  again  in  the  spring.  In  midsummer  many  of 
the  small  insects  near  the  surface  will  escape  injury 
from  treatment.  Carbon  bisulphid  may  also  prove 
useful  for  the  destructive  nematode  worms. 

For  borers  in  trunks  of  trees  clean  out  the  mouth  of 
the  burrow  and  insert  a  small  quantity  of  carbon  bisul- 
phid and  close  the  hole  with  thick  clay  or  other 
material.  The  borers  are  easily  killed  without  injury 
to  the  tree.  The  saving  of  time  fully  pays  for  the 
small  amount  of  carbon  bisulphid  required.  A  spring- 
bottom  oil-can  may  be  used  for  applying  the  liquid. 

Melon  plant-lice  can  be  treated  successfully  with 
carbon  bisulphid.  The  method  consists  in  covering 
the  young  vines  with  tight  boxes,  12  to  18  inches  in 
diameter,  made  of  wood  or  paper,  and  introducing 
under  each  box  a  saucer  containing  one  or  two  tea- 
spoonfuls  of  carbon  bisulphid.  The  vines  of  older 
plants  may  be  gathered  about  the  hill  and  folded  under 
large  boxes  or  tubs.  In  such  cases  a  greater  but  pro- 
portional amount  of  material  must  be  used.  The 
covering  is  usually  left  over  the  plants  from  three- 
quarters  to  an  hour.  With  50  to  100  boxes  a  field 
may  be  treated  quite  rapidly.  This  method  of  intro- 
ducing the  bisulphid  can  be  improved  by  boring  a  hole 
about  one  inch  in  diameter  in  the  middle  of  the  top  of 
each  box,  and  fastening  a  small  bunch  of  cotton- waste, 
rags,  or  any  absorbent  material.  By  fitting  a  stopper 


270  FUMIGATION   METHODS 

in  the  hole  the  box  Js  ready  for  use.  In  placing  it 
over  a  plant,  be  careful  that  the  edges  set  firmly  into 
the  dirt.  Remove  the  stopper,  add  the  desired  amount 
of  liquid,  and  close  it  quickly. 

Fumigation  of  mills  and  other  buildings. — Carbon 
bisulphid  can  be  thrown  directly  upon  grain  without 
injuring  its  edible  qualities,  and  will  not  effect  its  vital- 
ity in  the  least.  In  mills  it  can  be  used  about  the 
machinery,  spouts  and  elevators  with  perfect  assurance 
that  the  manufactured  products  will  not  be  damaged. 
I  know  of  no  instance  where  the  slightest  deleterious 
effect  has  been  realized  by  persons  applying  it  in  mills, 
although  they  unavoidably  inhale  some  of  the  fumes. 

The  amount  of  liquid  to  be  used  depends  ( i )  on  the 
size  of  the  building,  (2)  on  its  tightness,  and  (3)  on 
the  magnitude  of  the  attack.  Where  the  building  is 
reasonably  tight  and  but  slightly  infested,  one  pound 
of  carbon  bisulphid  is  sufficient  for  every  thousand 
cubic  feet  of  air-space  enclosed.  If  it  is  somewhat  open 
or  badly  infested  the  amount  should  be  doubled.  When 
applied  to  bins  containing  stored  grain,  one  pound  of 
liquid  to  every  hundred  bushels  of  grain  is  commonly 
used  ;  but  if  the  insects  are  very  abundant,  twice  this 
amount  should  be  used. 

Methods  of  application. — A  number  of  ways  for  using 
carbon  bisulphid  have  been  suggested  and  tested.  The 
most  effective  manner  of  applying  it  in  mills  consists  in 
simply  pouring  the  liquid  into  shallow  dishes,  such  as 
soup-plates,  pans,  or  wooden  vessels,  and  distributing 
them  about  the  building.  Bits  of  cotton-waste  satu- 
rated with  the  liquid  should  also  be  thrust  into  spouts, 


FUMIGATION   WITH    CARBON   BISUIyPHID          271 

elevator  legs,  machines,  and  other  places  where  the 
pests  usually  congregate  in  great  numbers.  Spraying 
or  throwing  the  liquid  broadcast  into  badly  infested 
corners,  on  machines,  and  other  pieces  of  apparatus 
where  the  pests  are  particularly  abundant,  has  been 
attended  with  very  good  results. 

Time  to  do  the  work, — Saturday  afternoon  is  the  best 
time  for  fumigating  a  mill  or  large  building.  After 
sweeping  from  top  to  bottom,  all  fires  about  the  premises 
should  be  extinguished  and  the  building  closed  as 
tightly  as  possible.  The  vessels  and  cotton-waste 
should  be  previously  distributed,  so  there  will  be  no 
unnecessary  delay.  The  number  and  distribution  of 
the  vessels  will  depend,  as  already  stated,  upon  the  con- 
dition of  the  mill  and  the  severity  of  the  attack.  It  is 
best  to  begin  with  the  lowest  story  and  work  upward. 
The  operators  can  then  keep  above  the  settling  gas. 
When  the  bisulphid  has  been  applied  throughout  the 
mill  it  should  be  locked  and  kept  closed  until  the  fol- 
lowing Monday  morning.  All  windows  and  doors 
should  then  be  thrown  wide  open  and  the  building 
allowed  to  air  an  hour  or  more  before  fire  is  started  in 
it.  Where  the  building  is  large  and  a  great  quantity 
of  material  has  been  used,  it  is  wise  to  have  a  watch- 
man stationed  outside  to  prevent  any  one  from  entering 
or  loitering  about  the  building  during  fumigation. 

Practical  application. — As  a  guide  to  those  who  may 
use  this  method,  I  quote  several  letters  from  practical 
millers  who  have  used  carbon  bisulphid  successfully. 
The  superintendent  of  a  large  Pennsylvania  milling 
company,  whose  name  I  withhold  by  request,  wrote  me 


272  FUMIGATION   METHODS 

the  following  letter.  •  It  is  a  valuable  contribution,  and 
should  be  read  by  every  wide-awake  miller  and  grain- 
dealer  :  '  *  We  have  delayed  answering  your  valued 
letter  until  we  were  able  to  report  the  result  of  our 
efforts  to  destroy  the  weevils  in  our  mill.  Following 
the  line  of  your  advice,  we  ran  our  stock  down  low  and 
thoroughly  renovated  our  mill  from"  top  to  bottom, 
cleaning  all  reels  and  purifiers.  We  then  fumigated 
the  whole  building  with  carbon  bisulphid.  We  dis- 
tributed 300  soup-plates  about  half  filled  with  bisul- 
phid through  the  mill,  and  saturated  balls  of  cotton 
with  the  same  material  and  placed  them  in  all  the  reels 
and  purifiers.  We  did  this  on  Saturday  night,  closed  the 
mill  tight  and  left  the  weevils  to  their  destruction. 

'  *  We  opened  the  mill  Monday  morning  and 
thoroughly  ventilated  it  before  entering  it.  We  found 
we  had  destroyed  thousands  of  the  pests,  and  in  the 
reels  and  purifiers  we  had  killed  them  all.  In  the 
course  of  a  few  days  a  few  insects  began  to  show  up  in 
the  cracks  in  the  floors  and  in  dark  corners.  Two 
weeks  later  we  repeated  the  dose  in  the  same  manner 
and  obtained  about  the  same  results.  In  the  mean 
time  we  whitewashed  the  mill  from  top  to  bottom 
(that  is,  every  place  that  could  be  covered) ,  putting  on  a 
good  heavy  coat.  We  have  reduced  the  bugs  to  a  very 
small  number,  and  eternal  vigilance  is  the  order  of  the 
day  with  us. 

' '  We  are  still  fighting  them.  Our  plan  is  to  keep 
a  stock  of  bisulphid  on>  hand  outside  of  the  main  build- 
ing. We  do  not  think  it  is  advisable  to  store  it  in  the 
mill.  Wherever  we  find  a  place  infested  by  the  weevil 
we  use  it  freely,  taking  care  to  do  it  when  the  mill  is 


FUMIGATION   WITH   CARBON   BISULPHID  273 

shut  down  and  closed  up  tight.  We  find  the  best 
results  from  the  use  of  carbon  bisulphid  can  be  obtained 
by  spraying  it  on  the  floors  and  in  infested  places.  We 
think  when  placed  in  plates  it  does  not  evaporate  quick 
enough  to  produce  the  death  atmosphere  required." 

Extra  precautions. — The  writer  has  called  atten- 
tion to  the  dangers  from  fire  when  the  fumes  of  carbon 
bisulphid  are  present.  Special  reference  is  now  made 
in  connection  with  the  treatment  of  buildings  with  this 
gas.  Not  even  a  lighted  cigar  or  pipe  should  be  al- 
lowed in  the  building.  Always  do  the  work  in  day- 
light. No  artificial  lights  of  any  kind  are  allowable. 
Bven  electric  lights  should  not  be  used.  When  turn- 
ing them  on  or  off  there  is  always  danger  of  producing 
a  spark,  which  might  prove  disastrous.  Heated  steam- 
pipes  should  be  allowed  to  cool  before  the  application  is 
made.  Electric  fans  should  not  be  run.  There  should 
be  no  heat  of  any  kind  in  the  building  while  the  vapor 
is  enclosed.  Owners  of  adjoining  premises  should  be 
informed  of  the  nature  of  the  work  being  done  and 
cautioned  to  be  on  their  guard  during  the  hours  of 
fumigation. 

Germination  of  seeds. — Fifty-four  varieties  of  seeds, 
including  the  principal  grain  and  garden  seeds,  were 
recently  treated  with  carbon  bisulphid  by  the  Division 
of  Botany,  United  States  Department  of  Agriculture. 
Every  precaution  was  taken  to  insure  uniformity  in 
the  seeds  of  each  lot,  treated  and  untreated.  The 
treated  lots  were  exposed  to  an  atmosphere  saturated 
with  carbon  bisulphid  vapor  for  forty-eight  hours. 
Under  the  most  extreme  treatment,  the  severity  of 


274  FUMIGATION   METHODS 

which  would  never»be  equaled  in  ordinary  practice,  a 
majority  of  the  varieties  tested  showed  no  injury  and 
germination  was  practically,  the  same  in  each  lot. 
Seeds  of  the  grass  family  appeared  more  tender  than 
other  kinds.  Experiments  were  also  conducted  upon 
grain  in  bulk,  using  the  liquid  at  the  rate  of  one  pound 
to  100  bushels  of  grain.  The  exposure  lasted  twenty- 
four  hours.  No  injury  could  be  detected  in  even  the 
most  delicate  seeds. 

Treating  seed  and  grain  in  bulk. — Such  seeds  as 
corn,  wheat,  rice,  peas,  beans,  cow-peas,  and  others 
are  frequently  attacked  by  insects  and  seriously  injured 
or  entirely  destroyed.  No  insecticide  now  known  is 
equal  to  carbon  bisulphid  for  the  destruction  of  such 
pests.  Seeds  or  grains  to  be  fumigated  should  be  placed 
in  barrels,  bins,  or  rooms.  The  enclosure  should  be 
tight.  Apply  the  carbon  bisulphid  as  directed  above, 
at  the  rate  of  from  one  to  one  and  a  half  pounds  for 
each  1,000  cubic  feet  of  space.  A  bin  or  room  ten  feet 
each  way,  or  1,000  cubic  feet,  will  hold  about  100 
bushels  of  grain.  A  barrel  or  small  enclosure  will 
require  a  larger  proportional  amount  unless  it  is  very 
tight.  Place  the  liquid  on  top  of  the  seed  in  shallow 
vessels.  A  small  bin  or  barrel  should  be  covered  with 
heavy  blankets  to  better  retain  the  vapor.  Close 
the  receptacle  for  24  or  36  hours.  The  germinating 
power  of  the  seed  will  not  be  injured  in  the  least,  other 
conditions  being  normal.  Rye,  millet,  barley,  and 
crimson  clover  are  the  most  liable  to  injury  and  should 
receive  proportionately  a  less  amount. 

As  many  of  these  pests  enter  the  seeds  in  the  open 
field  while  the  grain  is  in  shock,  stack,  or  growing,  it  is 


FUMIGATION   WITH   CARBON   BISULPHID  275 

desirable  to  fumigate  large  bulks  of  grain,  etc. ,  a.s  soon 
as  possible  after  it  is  put  in  store.  This  is  especially 
true  of  wheat,  corn,  peas,  and  beans,  particularly  those 
to  be  used  for  propagating  purposes  later.  L,arger 
warehouses  or  granaries  can  be  successfully  treated  if 
the  directions  cited  above  are  followed.  With  large 
bulks  of  grain  the  vapor  may  be  left  for  two  or  three 
days,  or  even  longer. 

Stimulating  effects  on  plants. — It  is  an  acknowledged 
fact  that  the  growth  of  plants  on  soil  following  treat- 
ment is  unusually  good.  Treatment  of  a  corn-field 
yielded  an  increase  of  46.8  per  cent,  in  the  grain  and 
21.73  Per  cent,  in  the  stover.  Potatoes  showed  an 
increase  in  weight,  varying  from  5.3  per  cent,  to  38.7 
per  cent.  In  a  series  of  experiments  upon  corn,  oats, 
beets,  potatoes,  and  clover,  much  the  same  results 
were  obtained,  but  the  most  marked  increase  was  in 
the  clover.  It  was  found  that  the  vapor  was  not 
detrimental  to  the  active  bacteria  causing  the  nodules 
upon  the  roots  of  this  legume,  but  rather  seemed  to 
favor  their  multiplication.  Furthermore,  it  was  found 
upon  these  same  plats  that  the  beneficent  influence  of 
the  treatment  was  quite  apparent  the  following  year, 
though  less  marked  than  it  had  been  the  first  year. 

EffeEl  upon  fruit. — Recently  an  Italian  investigator, 
M.  F.  Sestini,  has  determined  the  effect  of  carbon  bi- 
sulphid  upon  fresh  fruits.  His  conclusions  are  as  fol- 
lows: One  volume  of  carbon  bisulphid  evaporated  in 
10,000  volumes  of  air  produces  no  alteration  in  the 
character  of  the  fruit  during  an  exposure  of  twenty- 
four  hours.  After  the  treatment  flavor  is  normal  and 


276  FUMIGATION   METHODS 

it  appears  that  the  perfume  of  each  fruit  gains  in  fine- 
ness and  intensity.  The  color  of  fruits  not  entirely 
sound  becomes  deeper,  especially  upon  those  parts  of 
their  surfaces  which  have  been  bruised  during  ripening 
or  from  defects  in  packing ;  it  is  thus  very  easy  to 
choose  carefully,  rejecting  such  fruit  as  could  not  have 
been  preserved. 

Woolens,  furs,  and  clothes. — Woolens,  furs,  and 
other  wearing  apparel  may  be  placed  in  a  tight,  paper- 
lined  trunk  or  a  large  box,  and  treated  with  carbon 
bisulphid.  When  stored  away,  place  a  shallow  dish 
holding  a  few  ounces  of  the  liquid  on  the  goods,  and 
spread  some  newspapers  over  the  top  and  close. 
No  further  attention  will  be  required  ;  but  if  the  box 
is  not  tight,  it  will  be  necessary  to  repeat  the  dose 
every  few  weeks  during  the  hot  weather.  An  excel- 
lent plan  is  to  provide  a  large  packing-chest  having  a 
close-fitting  cover.  By  boring  a  hole  through  the 
cover  and  fastening  a  small  sponge  or  bit  of  cotton- 
waste  inside,  it  may  be  fumigated  by  pouring  the  bi- 
sulphid through  the  hole  upon  the  absorbent  when  it 
is  necessary.  Carpets,  rugs,  robes,  etc.,  can  be  freed 
of  all  pests  if  fumigated  for  a  few  days  in  such  a  box. 
The  odor  is  less  persistent  in  the  goods  than  that  of 
moth  balls,  tarred  paper,  or  other  materials.  When 
used  on  fine  fabrics  it  will  not  stain  or  injure  the  most 
delicate  articles,  provided  the  pure  carbon  bisulphid  is 
gotten. 

Such  household  pests  as  cockroaches,  fish  moths, 
bedbugs,  fleas,  carpet-beetles,  etc.,  can  be  destroyed 
in  tight  rooms  by  a  liberal  application  of  carbon  bisul- 


FUMIGATION   WITH    CARBON   BISULPHID  277 

phid.  Frequently  the  holds  of  ships  are  cleared  of  pests 
in  this  manner.  The  liquid  is  quite  generally  used  for 
the  destruction  of  a  number  of  insects  commonly  called 
museum  pests.  When  specimens  are  inclosed  in  fairly 
tight  showcases  or  trays,  they  can  be  easily  treated  in 
the  cabinet  or  drawer.  As  a  measure  of  safety,  in 
many  museums  the  fumigation  is  done  annually, 
regardless  of  the  absence  or  presence  of  the  pests. 

Killing  prairie-dogs,  gophers,  squirrels,  etc. — For 
the  destruction  of  small  animals  that  burrow  under 
ground,  such  as  prairie-dogs,  gophers,  woodchucks, 
squirrels,  moles,  rats,  mice,  etc.,  nothing  has  been 
used  with  such  gratifying  results  as  carbon  bisulphid. 
Some  years  ago,  when  the  writer  was  located  at  the 
University  of  Illinois,  several  plots  of  land  on  the 
Experiment  Station  farm  were  overrun  with  gophers. 
Their  presence  greatly  interfered  with  the  experiments 
being  conducted,  and  carbon  bisulphid  was  used  to 
destroy  them.  The  holes  or  burrows  were  located.  A 
piece  of  cotton  about  the  size  of  a  hen's  egg  was  satu- 
rated with  the  liquid,  thrust  into  the  hole,  and  closed 
with  a  small  piece  of  sod  and  loose  dirt  stamped  down 
firmly.  A  few  hours  later  several  of  the  burrows  were 
opened,  and  in  every  case  a  dead  animal  was  found 
with  its  nose  thrust  into  the  cotton.  It  evidently  had 
made  an  attempt  to  escape  the  deadly  vapor. 

Amount  to  use. — A  pint  of  carbon  bisulphid,  a  lit- 
tle more  than  a  pound,  is  sufficient  to  treat  twenty 
ordinary  burrows.  The  amount  used,  however,  de- 
pends somewhat  upon  the  size  and  character  of  the 
burrow.  If  rather  small  and  in  a  somewhat  compact 


278  FUMIGATION   METHODS 

soil,  a  small  quantity  will  suffice  ;  but  if  the  burrow  is 
large,  rather  shallow,  and  with  several  openings  lead- 
ing to  the  surface,  much  more  liquid  will  be  required. 
As  a  rule,  a  small  wad  of  cotton;  wool,  old  rags,  excel- 
sior, even  dry  grass  or  a  corn-cob,  saturated  with  a 
little  less  than  one  ounce  of  the  liquid  and  heeled  in 
the  holes,  will  do  the  work.  A  Nebraska  farmer  says 
he  uses  dried  balls  of  horse  manure.  They  hold  the 
liquid  well,  are  less  expensive  than  cotton,  and  easily 
obtained. 

On  the  Laramie  Experiment  Farm  in  Wyoming 
ninety -six  burrows  were  treated  during  the  month  of 
July.  The  applications  were,  with  few  exceptions, 
made  in  the  evening.  The  next  day  the  treated  bur- 
rows were  visited,  and  in  no  instance  had  the  earth 
which  had  been  used  for  plugging  the  opening  been 
disturbed.  A  second  and  third  visit  to  these  burrows 
found  them  securely  plugged.  In  two  instances  some 
animal,  presumably  a  ground  squirrel,  had  made  an 
effort  to  dig  open  the  burrow  from  the  outside.  The 
opening  extended  only  to  the  ball  of  cotton,  when,  from 
all  appearances,  the  task  was  given  up.  In  forty -three 
instances  gophers  (squirrels)  were  driven  or  seen  going 
into  the  burrows  and  treated  at  once.  None  of  the 
animals  ever  again  saw  daylight. 

It  is  best  to  perform  the  work  in  the  evening,  other- 
wise some  of  the  treated  burrows  will  be  dug  open  by 
out-lying  squirrels.  The  remedy  can  best  be  applied 
in  the  spring,  while  the  ground  is  yet  compact.  Where 
the  balls  of  dried  horse-dung  are  used  the  cost  is 
reduced  and  the  rounded  masses  carry  the  chemical 
beyond  the  reach  of  the  dirt  used  in  closing  the  hole. 


FUMIGATION   WITH   CARBON    BISUUPHID  279 

At  the  Idaho  Experiment  Station  a  test  was  made  upon 
thirty  holes.  Twenty-seven  of  these  were  undisturbed; 
two  were  scratched  open  from  the  outside  and  one 
from  the  inside.  Several  holes  were  afterward  dug 
open  and  in  each  was  found  a  dead  squirrel. 

Expert  opinions. — There  have  been  many  exagger- 
ated reports  about  the  nature  of  this  chemical  com- 
pound. In  this  connection  I  can  do  no  greater  service 
than  to  quote  a  letter  from  Edward  R.  Taylor,  the 
leading  manufacturer  of  carbon  bisulphid  in  this 
country.  He  says  :  "I  have  seen  a  great  many  very 
random  statements  on  the  subject  of  the  inflamma- 
bility of  carbon  bisulphid.  One  says,  '  Use  the  same 
care  as  with  gunpowder  '  ;  another  says,  '  it  is  a  very 
explosive  liquid.'  These  are  both  very  misleading 
statements  with  reference  to  its  properties.  I  have 
quoted  the  statements,  however,  in  my  printed  matter 
for  the  reason  that  farmers  and  many  others  use  the 
goods,  and  will  be  sufficiently  startled  by  such  state- 
ments to  be  careful  and  have  no  light  or  fire  about. 

' '  Nearly  everybody  is  now  familiar  with  gasoline. 
The  properties  of  that  liquid  and  carbon  bisulphid  are 
practically  identical,  in  that  both  are  inflammable  but 
neither  of  them  explosive.  The  vapor  of  either  of 
them  mixed  with  air  is  explosive,  but  the  liquids  are 
not  explosive.  I  have  shipped  thousands  of  pounds 
of  bisulphid  to  millers,  elevator  operators,  and  farmers, 
and  have  yet  to  have  the  first  report  of  any  disaster, 
even  of  the  most  trivial  character.  Need  I  say  more  ? 
My  directions  are  explicit.  Do  the  work  Saturday 
afternoon  by  daylight.  Have  absolutely  no  light  or 
fire  of  any  kind  about.  Close  the  building  and  leave 


28O  FUMIGATION   METHODS 

the  bugs  to  their  c^estrudlion  till  Monday  morning, 
Then  open  doors  and  windows,  and  thoroughly  venti- 
late before  going  to  work." 

The  vapor  of  carbon  bisulphid  takes  fire  in  air  at 
about  300°  F.  and  burns  with  a  faint  blue  flame,  diffi- 
cultly visible  in  daylight,  but  evolving  considerable 
heat  and  decomposing  the  carbon  bisulphid  into  carbon 
dioxide  (CO,)  and  sulphur  dioxide  (SO2).  The  latter 
is  the  familiar  gas  given  off  by  the  burning  of  sulphur 
matches  and  is  a  strongly  poisonous,  suffocating  gas 
which  should  not  be  inhaled.  Carbon  bisulphid  vapor 
mixed  with  three  times  its  volume  of  oxygen,  or  an 
amount  of  air  containing  that  amount  of  oxygen,  forms 
a  mixture  which  is  very  highly  explosive  upon  ignition. 
As  21  per  cent,  of  the  air  is  oxygen,  one  volume  of 
liquid  carbon  bisulphid  evaporated  in  5,357  volumes  of 
air  would  form  such  a  mixture.  An  atmosphere  com- 
posed of  one  volume  of  carbon  bisulphid  vapor  to 
approximately  14.3  volumes  of  air  is  liable  to  violent 
explosion  in  the  presence  of  fire  of  any  kind  whatever, 
or  a  temperature  of  about  300°  F.  without  flame.  We 
have  here  about  the  maximum  danger-point  from 
explosion  in  the  use  of  carbon  bisulphid. 

Exterminating  the  flour  moth. — My  experience  with 
the  Mediterranean  flour  moth  is  of  nearly  seven  years' 
standing.  Until  I  took  charge  of  my  mill  six  years 
ago  I  had  never  seen  nor  heard  of  the  insect,  and  when 
I  found  it  here  and  learned  what  it  was  I  doubted 
whether  such  a  delicate  little  creature  could  do  any 
more  harm  than  a  house-fly.  I  soon  had  evidence, 
however,  of  its  capacity  for  mischief.  For  one  day  it 


FUMIGATION   WITH    CARBON   BISULPHID  28 1 

actually  succeeded  in  shutting  down  our  100  h.  p.  en- 
gine by  so  choking  conveyors,  elevators,  etc. ,  with  its 
webs  that  the  wheels  simply  could  not  turn.  This  is 
an  absolute  fadl.  Meanwhile  I  had  written  to  Prof. 
W.  G.  Johnson,  the  expert,  about  the  pest  and  sent 
him  a  sample  of  its  work.  When  the  mill  was  finally 
choked  to  a  standstill  I  knew  what  to  do:  I  first  put 
six  men  at  work  taking  spouts  and  elevator  legs  apart 
and  cleaning  them  thoroughly,  and  when  that  was 
done  I  had  them  go  for  the  machines.  It  took  us  just 
six  days  to  get  cleaned  up.  Under  the  Professor's 
advice  I  had  provided  ten  gallons  of  carbon  bisulphid 
and  about  200  tin  pie-plates.  Saturday  afternoon  we 
closed  and  packed  all  the  doors  and  windows,  distrib- 
uted the  plates  throughout  the  mill,  filled  them  with 
bisulphid,  and  "let  her  simmer  "  until  Monday  morn- 
ing. Opening  up  the  mill  we  found  dead  moths  every- 
where.— L.  C.  SCHROEDER,  New  York. 

Some  insurance  companies  were  a  little  uneasy  lest 
they  should  suffer  loss  by  fire  originating  from  the 
use  of  carbon  bisulphid  in  mills.  The  American 
Miller  investigated  this  subject  by  sending  letters  of 
inquiry  to  all  the  important  millers'  insurance  com- 
panies in  the  United  States  and  Canada,  and  did  not 
learn  of  a  single  fire  known  to  have  been  caused  by 
the  use  of  carbon  bisulphid.  The  properties  of  the  fluid 
have  been  fully  described  above,  and  millers  have  been 
warned  to  keep  lights  and  fire  away  from  the  vapor, 
lest  an  explosion  should  occur.  The  fact  that  it  has 
been  used  so  long  without  fires  being  traceable  to  it 
gives  strength  to  the  opinion  that  millers,  out  of  con- 
sideration for  their  own  lives,  have  heeded  the  warning 


282  FUMIGATION    METHODS 

and  have  been  exceedingly  careful  in  applying  it.  It 
should  not  be  stored  near  the  mill,  as  this  increases  the 
fire  risk.  A  break  in  the  can  or  drum  might  unex- 
pectedly release  fumes  which  would  soon  fill  the  mill. 
Death  to  weevils. — Carbon  bisulphid  settled  the 
weevil  family  in  our  mill.  It  was  so  full  of  them  we 
thought  we  would  have  to  abandon  it  for  a  time.  Bi- 
sulphid cleaned  them  out  and  saved  us.  — A.  Wii,- 
HEiyM,  Ohio. 

All  a  miller  wants  for  weevils  and  other  mill  pests  is 
"  Fuma  "  carbon  bisulphid.  It  knocked  them  out  for 
us. — J.  C.  BRIGHT  &  SON,  West  Virginia. 

Exterminating  moles. — When  there  were  indications 
of  moles  to  be  seen,  we  found  the  run,  and  inserted  a 
ball  of  cotton  thoroughly  saturated  with  * '  Fuma  ' '  in 
each  opening.  The  earth  was  firmly  packed  over  the 
opening.  As  these  little  animals  have  so  many  turns 
to  their  paths,  I  followed  the  run  and  put  in  eight  more 
well-saturated  cotton  balls,  always  being  careful  to 
pack  the  earth  firmly  over  the  opening.  Anything 
worth  doing  at  all  is  worth  doing  well.  We  were 
about  discouraged,  as  the  moles  were  fast  destroying  a 
lawn  we  were  anxious  to  save.  We  determined  to 
give  "  Fuma  "  a  trial,  and  am  glad  we  did,  as  we  were 
soon  rid  of  moles. — A.  B.  SWAN,  Long  Island. 

Destroying  woodchucks. — I  have  always  had  my 
share  of  woodchucks,  and  I  never  could  get  rid  of  them 
until  last  season.  I  got  an  ounce  of  carbon  bisulphid, 
used  one-half  on  three  burrows,  and  in  about  three 
hours  all  three  had  been  dug  out.  I  used  the  other 
half  where  an  old  one  had  young;  the  next  morning  I 


FUMIGATION  WITH   CARBON  BISULPHID          283 

dug  out  the  hole  and  found  them  dead.  A  neighbor 
joined  with  me  and  we  got  twenty  pounds  of  carbon 
bisulphid.  One  pound  is  enough  for  fifty,  and  not  one 
has  ever  dug  out  of  the  hundreds  that  we  have  treated, 
unless  there  was  some  opening  that  we  missed.  Pour 
from  one  to  two  spoonfuls  on  anything  that  will  absorb 
the  stuff,  push  it  into  the  hole  three  feet,  push  down  a 
sod  nearly  to  it,  hoe  on  earth  and  tramp  down.  Treat 
all  main  outlets  the  same,  and  next  summer  one  will 
be  puzzled  to  find  the  place. — A.  B.  JOHNSON,  New 

York. 

Destruction  to  prairie- dogs. — I  cleared  a  pasture  of 
eighty  acres  with  fifty  pounds  of  carbon  bisulphid  and 
not  a  dog  showed  up  all  summer.  Five  or  six  came 
from  another  town  late  in  the  fall,  but  I  soon  put  them 
to  sleep  and  they  have  not  waked  up  yet.  It  is  the 
cheapest  means  by  which  prairie  dogs  can  be  destroyed. 

—THOMAS  SHEFFRAY,  Nebraska. 

I  have  destroyed  the  prairie-dogs  on  about  eighty 
acres  at  a  cost  of  $30.  This  one  operation  increased 
the  value  of  the  land  $500.  One  pound  of  of  carbon 
bisulphid  will  treat  twenty-five  holes. — ISAIAH  L,IGHT- 
NER,  Platte  County ',  Nebraska. 

We  killed  the  prairie-dogs  on  about  a  hundred 
acres  with  five  gallons  of  carbon  bisulphid.  It  is 
the  best,  as  well  as  the  cheapest,  way  of  getting  rid  of 
them. — Kansas  Farmer. 

Rats  and  mice  easily  destroyed. — Some  years  ago  the 
writer's  attention  was  called  to  a  granery  in  Maryland, 
under  which  a  large  number  of  rats  had  burrowed  into 
the  ground.  The  building  was  double,  set  on  posts 


284  FUMIGATION   METHODS 

raised  about  eighteen  tnches  above  the  ground,  with  a 
driveway  between.  The  earth  underneath  was  com- 
pletely honeycombed  with  burrows.  Two  pounds  of 
carbon  bisulphid  were  secured.  Wads  of  cotton,  vary- 
ing in  size  from  a  hen's  egg  to  one's  fist,  were  saturated 
and  thrust  into  every  burrow  that  opened  on  the  sur- 
face. The  holes  were  securely  closed.  Only  in  two 
instances  were  the  holes  opened  by  their  occupants, 
and  these  were  quickly  destroyed  by  a  second  dose. 
Wherever  a  burrow  is  found  about  any  building  it  can 
be  treated  in  the  same  way. 

In  fields  where  rats  and  mice  frequently  do  serious 
injury  to  corn  and  other  grain  in  shock  they  can  be  de- 
stroyed by  saturating  a  small  wad  of  corn-silk  or  husks 
and  pushing  them  in  the  holes  after  the  shock  has  been 
overturned.  Frequently  cellars  and  root-houses  are 
infested  with  rats.  A  few  ounces  of  carbon  bisulphid 
used  as  indicated  will  exterminate  them. 

How  carbon  bisulphid  is  put  up. — This  material  is 
usually  put  up  in  steel  drums  holding  fifty  pounds 
each  and  costs  about  ten  cents  a  pound.  It  can  be 
purchased  from  local  dealers  in  smaller  quantities.  In 
such  cases  the  price  is  about  double  that  quoted,  or 
even  more.  The  grade  known  as  Fuma  carbon  bisul- 
phid is  cheaper  than  the  chemically  pure  article.  Only 
in  rare  cases  is  it  necessary  to  use  the  pure  bisulphid. 
For  general  insecticide  purposes  ' '  Fuma  ' '  is  the 
standard  and  entirely  satisfactory.  The  writer  has 
used  large  quantities  of  it  with  most  excellent  results 
in  every  case. 


CHAPTER  XXII 

LAWS  REGULATING   NURSERY  AND   ORCHARD 
INSPECTION  AND  FUMIGATION 

>R  many  years  California  has  been  protecting 
her  horticultural  interests  by  strictly  en- 
forcing laws  enacted  for  that  purpose.  That 
State  was  the  pioneer  in  this  movement,  and 
the  benefits  arising  therefrom  have  been  very  marked. 
Not  only  have  California  orchards  been  greatly  in- 
creased in  area,  but  many  dangerous  insect  pests  and 
diseases  have  been  kept  out  by  the  vigilance  of  the 
quarantine  officers.  With  the  invasion  of  the  San 
Jose  scale  in  the  Eastern  States,  various  local  laws 
have  been  passed  to  meet  conditions  prevailing  in 
many  states  or  territories. 

In  Maryland,  Delaware,  and  Canada  the  fumiga- 
tion of  all  nursery  stock  with  hydrocyanic  acid  gas  is 
required.  North  Carolina  has  recently  adopted  fumi- 
gation methods,  and  nurserymen  in  that  State  will  be 
required  to  fumigate  all  trees  offered  for  sale.  In 
New  York  and  Montana  the  inspection  laws  require 
fumigation  of  all  nursery  stock  if  thought  necessary. 
In  Oregon  all  apple,  pear,  or  other  stock  grown  on 
apple  roots  must  be  fumigated  before  delivery.  Con- 
ditions are  such  that  other  states  will  soon  be  obliged 
to  incorporate  in  their  laws  the  fumigation  require- 

285 


286  FUMIGATION   METHODS 

ment  with  rules  regulating  the  inspection  of  nurseries. 
Maryland  has  done  more  in  perfecting  fumigation 
methods  in  the  East  than  any  other  State.  The 
Canadian  government  practically  adopted  the  Maryland 
system,  after  sending  a  representative  to  familiarize 
himself  with  details  and  methods  used  in  that  State. 

The  following  states  and  territories  have  no  laws  at 
present,  December  i,  1901,  governing  the  transporta- 
tion or  inspection  of  nursery  stock  :  Alaska,  Alabama, 
Arizona,  Arkansas,  Kansas,  Maine,  Minnesota,  Missis- 
sippi, Nebraska,  Nevada,  New  Hampshire,  Oklahoma, 
Rhode  Island,  South  Dakota,  Texas,  Vermont,  and 
Wyoming.  If  special  information  is  desired  relative 
to  inspection  or  the  shipment  of  nursery  stock  into 
any  of  the  above  states  or  territories,  it  can  be  secured 
through  the  Directors  of  Experiment  Stations. 

A  brief  synopsis  of  the  horticultural  laws  and 
rulings  regulating  the  inspection  of  nurseries  and 
orchards,  and  the  shipment  of  nursery  stock  in  the 
various  states  and  territories  is  given  herewith.  Most 
states  require  copies  of  the  authorized  certificate  of 
inspection  to  accompany  and  be  attached  to  each  con- 
signment of  nursery  stock.  Oregon,  Colorado,  Idaho, 
and  Montana  require  all  nursery  stock  entering  their 
borders  to  be  inspected  by  local  inspectors.  Canada 
receives  no  stock,  as  noted  in  Chapter  XXIII.,  except 
through  certain  ports  of  entry,  where  it  is  fumigated. 
This  is  true  also  in  Montana  and  Oregon.  All  stock 
shipped  into  New  York  from  other  states  must  be 
fumigated.  Nurserymen  desiring  to  ship  into  those 
states  should  bear  this  in  mind  and  look  up  the  points 
of  entry.  Duplicate  certificates  are  required  for  ship- 


INSPECTION   AND   FUMIGATION   LAWS  287 

merit  of  nursery  stock  into  Georgia,  Michigan,  Ohio, 
North  Carolina,  South  Carolina,  and  Virginia. 

California. — The  State  Quarantine  Officer  at  San 
Francisco,  Cal.,  must  be  notified  of  the  receipt  of  nurs- 
ery stock,  pits,  fruits  or  vegetables,  which  must  beheld 
for  inspection.  Any  consignment  found  infested  with 
injurious  insects  or  plant  diseases  shall  be  treated  under 
the  direction  of  the  quarantine  officer.  If  the  ship- 
ment is  found  to  contain  pests  not  established  in  the 
State,  the  entire  consignment  shall  be  destroyed  or 
sent  out  of  the  State.  Any  nursery  stock  affected  by 
yellows  or  rosette  will  be  destroyed  or  returned  to  the 
consignee.  The  county  boards  of  horticulture  cause 
the  inspection  of  nurseries,  orchards,  vegetables,  vines, 
and  fruits.  Owners  are  obliged  to  suppress  injurious 
insect  pests  if  found  on  their  premises. 

Colorado. — The  regulations  for  the  prevention  of 
diseases  in  orchards  and  nurseries  are  placed  in  the 
hands  of  the  State  Board  of  Horticulture.  County 
inspectors  are  appointed,  and  they  must  examine  all 
shipments  of  nursery  stock  before  delivery.  If  found 
infested,  they  shall  be  disinfected,  destroyed,  or  re- 
moved from  the  county,  at  the  option  of  the  inspector. 
An  orchard,  nursery,  fruit-packing  house  or  storeroom 
found  infested  with  injurious  insect  pests  or  diseases 
dangerous  to  fruit  trees,  vines,  or  the  horticultural  in- 
terests in  general,  must  be  disinfected  or  treated  ac- 
cording to  the  direction  of  the  county  inspector.  If 
he  shall  neglect  or  refuse  to  treat  or  destroy  as  directed, 
the  owner  shall  be  guilty  of  maintaining  a  nuisance, 
and  liable  to  a  fine.  If  found  guilty,  the  inspector  has 


288  FUMIGATION   METHODS 

a  right  to  abate  the  jiuisance  at  the  expense  of  the 
owner. 

Connecticut. — The  State  Entomologist,  who  shall 
have  an  office  at  the  Experiment  Station  at  New 
Haven,  Conn.,  under  the  direction  of  the  Board  of 
Control  of  the  Connecticut  Agricultural  Experiment 
Station,  has  charge  of  the  nursery  and  orchard  inspec- 
tion in  that  State.  All  nursery  stock  shipped  from 
other  states,  counties,  or  provinces  shall  bear  a  certifi- 
cate. In  case  a  shipment  is  made  not  bearing  a  cer- 
tificate, it  can  be  inspected  by  the  State  Entomologist 
at  the  request  of  the  owner,  and  if  found  free  from 
pests  and  disease  it  may  be  received,  and  the  cost  of 
inspection  deducted  from  the  consignor's  bill  for  said 
stock.  All  nurseries  in  the  State  shall  be  inspected  at 
least  once  a  year,  and  if  no  serious  pests  are  found  a 
certificate  to  that  effect  is  given  to  the  owner.  If  pests 
of  a  dangerous  character  are  discovered,  the  owner  is 
required  to  suppress  the  same  under  the  direction  of 
the  State  Entomologist.  This  act  went  into  effect 
July  i,  1901. 

Delaware. — The  orchards  and  nurseries  of  the  State 
must  be  inspected  at  least  once  a  year  by  the  inspector 
authorized  by  the  State  Board  of  Agriculture  at  Dover, 
Del.  Nursery  stock  shipped  into  the  State  must  be 
accompanied  by  a  certificate.  Since  August  i,  1901, 
nurserymen  are  required  to  fumigate  all  stock  offered 
for  sale  or  shipment. 

Florida. — A  penalty  for  knowingly  selling  diseased 
nursery  stock  is  provided  by  the  statutes,  but  they  are 
inoperative.  The  Entomologist  at  the  Experiment 


INSPECTION   AND   FUMIGATION   LAWS  289 

Station   at   Lake    City,    Fla.,    issues    certificates   to 
nurserymen  in  the  State  upon  request. 

Georgia. — A  State  Entomologist  is  appointed  by 
the  State  Board  of  Entomology,  with  headquarters  at 
Atlanta,  Ga.  The  Board  formulates  rules  for  the 
treatment  or  destruction  ot  trees,  and  prevent  whenever 
possible  the  introduction  of  any  pests  considered 
dangerous  to  the  horticultural  interests.  A  certificate 
from  the  State  Entomologist  must  accompany  all  stock 
shipped  by  nurserymen  of  the  State.  Nurserymen 
from  other  places  desiring  to  ship  into  Georgia  must 
file  a  copy  of  their  accredited  certificate  of  inspection 
with  the  Commissioner  of  Agriculture  at  Atlanta,  Ga. 
When  the  proper  certificate  is  filed  by  nurserymen  from 
without  the  State,  the  State  Board  of  Entomology  will 
issue  its  certificate  permitting  shipment  of  stock  into 
the  State.  Official  tags,  bearing  a  facsimile  of  this 
certificate,  are  required  and  will  be  furnished  by  the 
Board  at  cost,  viz. :  Fifty  cents  for  the  first  one  .hundred 
and  twenty-five  cents  for  each  additional  hundred. 

Idaho. — A  general  State  inspector  and  ten  district 
inspectors  are  appointed  by  the  State  Board  of  Hor- 
ticulture at  Moscow.  These  officials  are  required  to 
inspect  orchards,  fruit  houses,  etc. ,  and  if  pests  of  a 
dangerous  nature  are  found  the  premises  may  be  dis- 
infected or  the  fruit  may  be  destroyed,  at  the  option  of 
the  officer  in  charge.  Peach,  nectarine,  apricot,  plum, 
almond  and  other  trees  budded  or  grafted  on  peach 
stock  grown  in  districts  where  peach  yellows  or  peach 
rosette  are  known  to  exist  are  prohibited  sale  or  dis- 
tribution in  the  State.  All  nursery  stock  offered  for 


2 QO  FUMIGATION   METHODS 

sale  from  other  sources  must  be  examined  by  the  in- 
spector, and  if  not  approved  it  must  be  destroyed.  To 
all  shipments  of  nursery  stock  intended  for  the  State 
shall  be  affixed  a  label  showing  the  contents,  together 
with  the  name  of  the  shipper  and  the  locality  where 
the  stock  was  gro\vn. 

Illinois. — The  State  Entomologist,  whose  office  is 
at  Urbana,  111.,  has  full  charge  of  the  nursery  and 
orchard  inspection.  Nurseries  are  inspected  annually 
and  certificates  granted,  copies  of  which  must  accom- 
pany all  shipments.  It  is  unlawful  for  transportation 
companies  to  deliver  nursery  stock  of  any  kind  within 
the  State  unless  such  stock  is  accompanied  by  a  certi- 
fied certificate  approved  by  the  State  Kntomologist. 

Indiana. — All  the  nurseries  of  the  State  shall  be 
inspected  at  least  once  a  year  by  the  State  Entomolo- 
gist, whose  office  is  at  Lafayette,  Ind.  Certificates 
of  inspection  are  given  to  nurserymen  within  the  State, 
and  copies  of  the  same  must  accompany  all  shipments. 
All  stock  received  from  other  states  must  bear  a  cer- 
tificate signed  by  State  or  government  inspectors. 

Iowa. — Quarantine  maybe  established  against  dan- 
gerous insects  and  plant  diseases  by  the  State  Ento- 
mologist at  Ames,  la.  Nurseries  are  inspected  at  least 
once  a  year  and  certificates  issued  accordingly.  It  is 
unlawful  to  bring  nursery  stock  into  the  State  unless 
accompanied  by  proper  certificate  from  an  authorized 
official. 

Kentucky. — The  nurseries  of  the  State  are  inspected 
at  least  once  a  year  by  the  State  Entomologist  at  Lex- 


INSPECTION   AND   FUMIGATION   LAWS  29! 

ington,  Ky.  Certificates  are  issued  when  the  stock 
is  found  in  good  condition,  and  whenever  a  nurseryman 
sells  trees,  vines,  plants,  or  other  nursery  stock,  he 
shall  attach  to  each  package  a  certificate  signed  by 
himself,  stating  that  the  contents  has  been  examined 
by  a  properly  certified  official  and  found  free  from  San 
Jose  scale  and  other  destructive  and  injurious  insect 
pests  or  fungus  diseases.  All  stock  shipped  into  the 
State  must  be  plainly  labeled  with  the  name  of  the 
consignor  and  the  consignee  by  the  State  or  govern- 
ment inspector.  Stock  arriving  without  certificate 
shall  be  returned  to  the  consignor  or  inspected  by  the 
State  Entomologist  at  the  expense  of  the  consignor; 
otherwise  it  will  be  burned. 

Louisiana. — It  is  unlawful  to  bring  into  the  State 
nursery  stock,  pits  or  any  kind  of  fruit  infested  with 
disease  or  insects  of  an  injurious  nature.  It  is  unlaw- 
ful to  propagate  or  offer  for  sale  any  such  stock.  All 
fruit  trees  and  other  nursery  stock  brought  into  the 
State  shall  be  labeled  with  the  name  of  the  owner  or 
grower,  the  locality  where  grown,  and  shall  be  subject 
to  inspection  by  the  Entomologist  of  the  Experiment 
Station  at  Baton  Rouge,  La.  It  is  the  duty  of  the 
owner  to  disinfect  or  destroy  any  fruit  trees  perniciously 
affected  with  disease. 

Maryland. — Co-operating  under  the  laws  creating  a 
State  Horticultural  Department,  the  State  Entomolo- 
gist and  State  Pathologist  are  required  to  inspect  once 
every  six  months  all  nurseries  within  the  State  and 
issue  certificates  to  the  owners.  All  nursery  stock 
shipped  must  be  accompanied  by  a  printed  copy  of  the 


2Q2  FUMIGATION   METHODS 

official  certificate  attached  to  each  package.  Nurseries 
are  compelled  to  fumigate  with  hydrocyanic  acid  gas 
all  stock  grown  or  handled  by  them  under  the  direction 
of  the  State  officers.  Every  package  of  nursery  stock 
shipped  into  the  State  must  be  plainly  labeled  with  the 
name  of  the  consignor  and  consignee  and  a  certificate 
showing  that  the  contents  has  been  inspected  by  the 
proper  official.  Transportation  companies  receiving 
nursery  stock  arriving  into  the  State  without  such 
certificate  must  send  notice  to  the  inspectors  at  College 
Park,  Md.  Failure  to  return  a  shipment  not  properly 
certified  renders  the  stock  liable  to  seizure  and  destruc- 
tion by  burning. 

Massachusetts, — The  Trustees  of  the  Agricultural 
College  at  Amherst,  Mass. ,  have  appointed  two  inspec- 
tors, who  inspect  all  nurseries  within  the  State  when 
called  upon  to  do  so.  All  certificates  expire  July  i 
following  the  date  of  issue. 

Michigan. — The  State  Inspector  of  nurseries  and 
orchards  is  appointed  by  the  State  Board  of  Agricul- 
ture, Lansing,  Mich.  All  orchards  and  nurseries  of 
the  State  are  properly  inspected  and  certified  and  cer- 
tificates issued  to  the  latter.  All  persons  growing  or 
offering  for  sale  any  nursery  stock  within  the  State  are 
obliged  to  apply  to  the  State  Board  of  Agriculture  and 
request  inspection  before  August  i  of  each  year.  A 
deposit  fee  of  $5.00  as  a  license  is  required,  the  license 
being  good  for  one  year  and  not  transferable.  Any 
person,  firm  or  corporation  resident  of  another  State 
shall  not  engage  in  the  business  of  selling  nursery 
within  the  State  without  first  having  a  proper  license 


INSPECTION   AND   FUMIGATION   LAWS  293 

from  the  State  Board.  A  bond  in  the  sumof$i,ooo  is 
required  on  condition  that  nurserymen  and  dealers 
will  comply  with  all  the  provisions  of  the  law,  and 
upon  demand  will  file  with  the  Board  a  list  of  the  per- 
sons to  whom  they  have  sold  or  delivered  any  nursery 
stock,  giving  the  species,  together  with  the  address  of 
each  purchaser.  Failure  on  the  part  of  any  nursery- 
man, grower,  agent  or  dealer  to  comply  with  these 
provisions  shall  render  him  liable  to  a  fine. 

Missouri. — An  inspector  is  appointed,  whose  duty 
it  is  to  visit  sections  of  the  State  and  prescribe  reme- 
dies for  diseased  trees  and  orchards.  Nursery  stock 
arriving  from  without  the  State  must  be  accompanied 
by  the  entomologist's  certificate,  and  no  package  can 
be  delivered  until  such  certificate  is  attached.  The 
work  is  under  the  general  direction  of  the  State  Board 
of  Agriculture,  Columbia,  Mo. 

Montana. — The  State  Board  of  Horticulture  shall 
appoint  an  inspector  of  fruit  pests  for  each  of  the  six 
districts.  The  nurseries,  orchards,  fruits,  etc.,  shall 
be  visited  regularly  and  the  regulations  of  the  Board 
enforced.  Every  person  selling  or  delivering  nursery 
stock  is  required  to  notify  the  inspector  at  least  five 
days  before  the  said  stock  is  to  be  delivered,  giving 
date  and  the  nursery  and  railroad  station  where  the 
said  stock  is  to  be  delivered.  It  shall  be  the  duty  of 
the  inspector  to  inspect  such  stock,  and  if  any  of  it  is 
found  infested  or  diseased  to  order  its  destruction. 

Under  the  ruling  of  the  Board  of  the  Inspectors  at 
large,  inspectors  shall  inspect  or  fumigate  all  nursery 
stock  growing  in  the  State,  and  shall  have  authority 


294  FUMIGATION   METHODS 

to  order  all  nursery  »stock  fumigated  with  hydrocy- 
anic acid  gas  or  other  method.  All  stock  shipped 
into  the  State  before  delivery  to  the  purchaser  must 
be  inspected  and  fumigated  as  follows  :  Consignment 
over  the  Northern  Pacific  R.  R.  from  the  West,  in- 
spected and  fumigated  at  Missoula;  over  the  Oregon 
Short  Line  from  the  South,  at  Dillon;  over  the  North- 
ern Pacific  R.  R.  from  the  East,  and  over  the  Burling- 
ton railway,  at  Miles  City  or  Billings;  over  the  Great 
Northern,  at  Kalispall;  over  the  Great  Falls  and  Can- 
ada Railway,  and  from  the  East  over  the  Great  North- 
ern Railway,  at  either  Glasgow,  Chinook,  Fort  Bentori 
or  Great  Falls.  Any  nursery  stock  brought  in  on 
wagons  or  otherwise  shall  be  inspected  and  fumigated 
at  the  nearest  quarantine  station. 

Importers  of  nursery  stock  may  have  an  inspection 
at  any  point  in  the  State  by  paying  the  expense 
thereof.  All  boxes,  packages,  or  wrappings  used  in 
importing  nursery  stock  shall  be  burned  as  soon  as 
emptied.  A  fee  of  $10  shall  be  charged  for  each  car 
load  to  cover  the  cost  of  inspection  and  fumigation. 
All  green  or  citrus  fruits  offered  for  sale  in  the  State 
shall  be  inspected,  and  if  found  free  of  disease  and 
infection  shall  be  branded  ' '  Inspected  and  passed. ' ' 
If  infested  they  shall  be  burned.  A  fee  of  two  cents 
per  box,  with  a  maximum  fee  of  $5  for  each  lot  in- 
spected, shall  be  exacted.  Every  person  offering  to 
sell  or  deliver  nursery  stock  in  the  State  shall  place  on 
each  package,  or  car,  a  label  stating  whether  or  not 
the  stock  was  grown  in  Montana.  General  informa- 
tion can  be  secured  from  the  Secretary  of  the  State 
Board  of  Horticulture,  Missoula,  Mont. 


INSPECTION  AND   FUMIGATION   LAWS  295 

New  Jersey. — Any  nurseryman  or  grower  of  plants 
offered  for  sale  may  require  the  State  Entomologist 
at  New  Brunswick,  N.  J. ,  to  examine  or  have  examined 
the  stock  grown  by  him.  If  no  injurious  insects  liable 
to  spread  are  discovered  he  may  demand  a  certificate  to 
that  effect.  All  nursery  stock  shipped  into  the  State 
must  be  accompanied  by  a  proper  certificate.  Any 
stock  received  without  a  certificate  may  be  detained  by 
the  State  Entomologist  or  his  deputy,  and  in  case  it  is 
found  infested  it  may  be  destroyed  or  reshipped  to  the 
original  shipper.  Florists'  stock  is  exempt  under  this 
act.  Not  more  than  three  commissioners  are  appointed 
for  each  county.  They  are  empowered  to  report  the 
presence  of  any  injurious  insects  or  diseases  liable  to 
spread  to  the  State  Entomologist,  who  may  order  such 
treatment  as  seems  best.  Persons  failing  to  carry  out 
the  instructions  of  the  State  Entomologist  shall  be 
fined. 

New  York.  — The  orchards  and  nurseries  of  the  State 
are  inspected  annually  under  the  direction  of  the  Com- 
missioner of  Agriculture,  Albany,  N.  Y.  Prior  to  the 
first  of  September  each  year  every  nursery  or  other1 
place  where  trees,  shrubs,  or  plants,  commonly  known 
as  nursery  stock,  are  grown  for  sale  must  be  inspected 
and  proper  certificates  issued  to  the  owner.  All 
nursery  stock  transported  in  any  manner  shall  be 
accompanied  by  a  copy  of  said  certificate  attached  to 
each  car,  box,  bale,  or  package.  All  transportation 
companies  within  the  State  receiving  or  carrying 
nursery  stock  from  any  point  without  the  State  to  any 
point  within  shall  immediately  upon  receipt  of  such 
consignment  notify  the  Commissioner  of  Agriculture, 


296  FUMIGATION   METHODS 

giving  the  name  of  the  consignor,  the  consignee,  and 
the  point  of  destination. 

If  in  the  judgment  of  the  Commissioner  of  Agri- 
culture, or  his  representative,  the  consignment  should 
be  entirely  destroyed,  such  destruction  shall  be  carried 
on  and  completed  under  the  supervision  of  the  person 
in  charge.  The  commissioner  shall  notify  the  owner 
of  the  trees  immediately,  giving  a  brief  statement  of  the 
facts,  and  calling  attention  to  the  law  under  which  it 
is  proposed  to  destroy  them.  In  case  of  objection 
to  the  findings  of  the  inspector  or  agent  of  the  Com- 
missioner of  Agriculture,  an  appeal  shall  be  made  to 
such  commissioner,  whose  decision  shall  be  final.  An 
appeal  must  be  taken  within  three  days  from  service 
of  said  notice  and  shall  act  as  a  stay  of  proceedings 
until  it  is  heard  and  decided. 

The  recent  law  passed  by  the  New  York  Legisla- 
ture, 1902,  requires  the  fumigation  of  all  nursery  stock 
coming  into  the  State  from  other  States.  When  fumi- 
gated by  the  consignor  a  certificate  should  be  attached 
indicating  same.  All  nurseries  within  the  State  located 
within  one-half  mile  of  a  district  infested  with  the  San 
Jose  scale  must  fumigate  all  their  nursery  stock  before 
shipment  or  distribution. 

North  Carolina. — No  person  shall  sell  or  give  away 
any  trees,  shrubs,  or  woody  vines  until  a  license  to 
deal  in  such  plants  has  been  previously  obtained  from 
the  Commission  Controlling  Crop  Pests  at  Raleigh, 
N.  C.  Certificates  previously  certified  must  accom- 
pany all  consignments  of  nursery  stock,  and  transpor- 
tation companies  shall  not  deliver  any  such  stock 
unless  a  certificate  is  attached  to  each  package.  All 


INSPECTION   AND   FUMIGATION   LAWS  297 

nursery  stock  not  properly  labeled  may  be  seized  or 
destroyed.  Transportation  companies  having  nursery 
stock  in  their  possession  not  properly  labeled  or  certi- 
fied shall  destroy  it  or  send  it  out  of  the  State  within 
forty-eight  hours,  if  brought  from  without  the  State  or 
otherwise.  All  licenses  to  sell  nursery  stock  issued  by 
the  commissioner  shall  bear  a  uniform  date,  April  ist 
or  October  ist,  and  shall  be  good  for  six  months  and 
no  longer. 

Licenses  to  dealers  shall  be  granted  to  residents  of 
the  State,  who  shall  sign  an  agreement  not  to  purchase 
nursery  stock  of  any  nursery  or  dealer  located  within 
or  without  the  State  unless  such  a  nursery  is  already 
licensed  by  the  commissioner.  Licenses  shall  be 
granted  only  to  agents  employed  by  licensed  nurseries 
or  dealers,  and  the  principals  shall  be  held  responsible 
for  the  stock  sold  by  such  agents.  No  fees  are  charged 
for  licenses,  but  nurserymen  and  dealers  will  be  required 
to  pay  the  actual  traveling  expenses  of  the  State  Ento- 
mologist who  is  sent  semi-annually  to  inspect  their 
establishments.  Nurserymen  outside  the  State  must 
send  their  official  certificates  properly  certified  to  the 
Department  of  Agriculture,  Raleigh,  N.  C.  One 
hundred  official  tags  will  be  furnished  free  of  charge 
to  the  nurserymen  filing  certificates.  Additional  tags 
will  cost  forty  cents  per  hundred.  One  of  these  tags 
must  be  attached  to  each  consignment  of  nursery  stock 
shipped  into  the  State. 

Ohio. — Not  later  than  August  15  all  nurseries  in 
the  State  shall  be  examined  annually  by  the  Inspector 
or  his  representative  appointed  by  the  Agricultural 
Experiment  Station  at  Wooster,  Ohio.  If  the  nurser- 


298       .  FUMIGATION   METHODS 

ies  appear  free  from,  dangerous  diseases  and  insect 
pests,  the  inspector  shall  give  each  owner  of  the  nurs- 
ery a  certificate  to  that  effect  on  receipt  of  $10  for  the 
first  day's  inspection,  and  $5  for  each  subsequent  day. 
Copies  of  said  certificate  must  accompany  all  ship- 
ments of  nursery  stock.  Bvery  package  of  nursery 
stock  shipped  into  the  State  must  be  accompanied  by 
a  copy  of  the  official  inspection  certificate.  Transpor- 
tation companies  are  required  to  report  to  the  Inspec- 
tor of  a  consignment  not  properly  certified. 

Oregon.—  The  State  is  divided  into  five  quarantine 
districts  by  the  State  Board  of  Horticulture.  All  con- 
signments of  nursery  stock  arriving  from  without  the 
State  must  be  inspected  on  arrival  at  the  quarantine 
station.  If  such  stock  is  found  free  from  pests  or  dis- 
eases, the  officer  in  charge  shall  issue  a  certificate  to 
that  effect.  If  any  trees  are  found  infested,  they  are 
to  be  disinfected  and  remain  in  quarantine  until  pro- 
nounced clean.  No  peach,  nectarine,  apricot,  plum  or 
almond  trees,  or  other  stock  worked  on  peach  roots,  or 
pits  or  cuttings,  buds  or  scions  of  such-named  trees 
grown  in  the  district  where  yellows  or  rosette  are 
known  to  exist,  shall  be  admitted  into  the  State. 

All  nursery  stock  from  foreign  countries  found  in- 
fested with  insects  or  diseases  hitherto  unknown  in  the 
State  are  not  allowed  to  land.  Nursery  stock  may  be 
disinfected  by  dipping  into  a  solution  of  whale  oil  soap, 
or  fumigated  with  hydrocyanic  acid  gas.  All  nurseries 
must  be  inspected  by  the  quarantine  officers  of  the  dis- 
trict in  the  months  of  September,  October,  or  Novem- 
ber prior  to  shipment  each  year.  Certificates  shall  be 
issued  where  the  stock  is  found  in  proper  condition, 


INSPECTION   AND   FUMIGATION  LAWS  299 

provided  the  owner  shall  fumigate  with  hydrocyanic 
acid  gas  all  pear  and  apple  trees,  or  other  stock  grown 
on  apple  roots  after  digging  and  before  delivery.  Gen- 
eral information  regarding  the  control  of  apple  pests 
may  be  had  by  addressing  the  State  Board  of  Horticul- 
ture, Salem,  Oregon. 

Pennsylvania.. — The  Secretary  of  Agriculture  at 
Harrisburg,  Pa.,  shall  have  all  nurseries  within  the 
State  examined  each  year.  If  found  free  from  dan- 
gerous insect  pests  and  other  diseases,  the  owner  shall 
receive  a  certificate.  Nurserymen  receiving  such  cer- 
tificate must  attach  a  copy  to  each  package  of  nursery 
stock  shipped.  Transportation  companies  shall  reject 
stock  not  accompanied  by  such  certificate.  Nursery 
stock  shipped  into  the  State  shall  be  plainly  labeled 
with  the  name  of  the  consignor  and  the  consignee,  and 
a  certificate  showing  that  the  contents  have  been  in- 
spected by  State  or  government  officers.  Greenhouse 
stock  is  exempt  under  the  provision  of  this  law. 

South  Carolina. — The  Board  of  Trustees  of  Clem- 
son  College  designates,  every  two  years,  three  of  their 
members  who  constitute  the  State  Board  of  Entomol- 
ogy. This  Board  has  full  power  to  adopt  rules  and 
regulations  governing  the  inspection,  certification,  sale, 
transportation,  and  introduction  of  nursery  stock. 
The  Entomologist  at  Clemson  College,  (P.  O.),  S.  C., 
shall  direct  the  work  and  inspect  each  nursery  in  the 
State  during  the  months  of  August  and  September  of 
each  year.  Infested  orchards  shall  be  treated  when- 
ever discovered.  The  owners  of  infested  orchards  or 
nurseries  shall  pay  all  cost  for  such  treatment,  except 


3OO  FUMIGATION   METHODS 

the  traveling  and  incidental  expenses  of  the  entomol- 
ogist. All  nurserymen  and  dealers  in  nursery  stock 
located  and  doing  business  within  the  State  limits  are 
required  to  accompany  all  stock  with  a  copy  of  the 
official  certificate  issued  them  by  the  inspector.  All 
certificates  are  invalid  after  June  i  of  each  year,  but 
must  be  renewed  before  October  i  of  the  same  year. 
All  persons  or  incorporations  without  the  State  who 
desire  to  sell  nursery  stock  in  South  Carolina  shall 
register  their  name  and  file  a  copy  of  their  certificate  of 
inspection  with  the  Chairman  of  the  Board  of  Ento- 
mology. Upon  failure  to  comply  with  this,  shipments 
may  be  destroyed. 

Tennessee. — Nursery  stock  cannot  be  oifered  for 
sale  in  Tennessee  without  a  certificate  from  the  State 
Entomologist  being  attached  to  each  package,  as  well 
as  the  name  of  the  consignor  and  consignee.  Certifi- 
cates are  valid  twelve  months  from  date  of  issue.  It 
is  the  duty  of  the  State  Entomologist  to  inspect  all 
nurseries  and  floral  establishments  when  he  deems  it 
necessary.  All  infested  nursery  stock  must  be  de- 
stroyed. Consignments  of  nursery  stock  from  other 
States  shipped  into  Tennessee  must  bear  certificates  of 
inspection,  as  well  as  the  name  of  the  consignor  and 
consignee.  Unless  a  certificate  is  attached  the  trans- 
portation company  receiving  same  must  notify  the 
State  Entomologist  at  Nashville.  A  fee  of  $5.00  is 
required  from  florists  and  nurserymen  who  have  less 
than  fifty  acres;  the  inspection  fee  is  $10.00  for  nur- 
series over  fifty  and  less  than  one  hundred  acres,  and 
$15.00  for  more  than  one  hundred  acres.  In  effect 
April  20,  1901. 


INSPECTION   AND   FUMIGATION   LAWS  301 

Utah. — The  State  Board  of  Horticulture  consists 
of  three  members,  each  representing  a  district.  It  is 
the  duty  of  every  owner  of  an  orchard,  vineyard,  or 
nursery  to  disinfect  trees,  vines,  or  nursery  stock  if 
affected  with  any  fruit-destroying  disease.  All  per- 
sons who  make  a  general  business  of  spraying  trees 
must  first  get  a  certificate  from  the  Board.  It  is  the 
duty  of  the  Board  to  have  inspected  all  orchards  and 
nurseries  within  the  State.  All  persons  or  nursery- 
men shall  report  to  the  inspectors  the  receipt  of  any 
trees  from  points  outside  of  the  State,  and  such  inspec- 
tors shall  examine  all  such  stock  as  well  as  stock 
grown  or  offered  for  sale  in  the  State.  General  infor- 
mation can  be  secured  from  the  State  Board  of  Horti- 
culture at  Logan,  Utah. 

Virginia. — The  rules  regulating  the  inspection  of 
orchards  and  nurseries  are  made  by  the  Board  of  Crop 
Pest  Commissioners.  No  person  shall  sell  or  trans- 
port any  fruit  trees  or  other  plants  when  infested  with 
woolly  aphis,  San  Jose  scale,  peach  yellows,  black 
knot  of  the  plum,  fire  blight  of  the  pear,  or  crown  gall. 
Any  nursery  found  infested  with  these  pests  shall  not 
be  entitled  to  a  certificate  until  such  pests  have  been 
eliminated  under  the  direction  of  the  inspector.  It  is 
unlawful  for  a  nursery  to  offer  for  sale  nursery  stock 
unless  accompanied  by  a  certificate  of  inspection.  All 
nursery  stock  entering  the  State  from  without  must 
be  accompanied  by  a  certificate  from  an  official  and  a 
competent  inspector.  The  State  Entomologist  and 
Pathologist  at  Blacksburg,  Va.,  shall  furnish  to  all 
nurserymen  in  other  states  doing  business  in  Virginia 
an  official  tag  upon  request,  if  the  certificate  of  inspec- 


302  FUMIGATION   METHODS 

tion  filed  by  said  nurseryman  from  without  is  found 
satisfactory.  Transportation  companies  can  not  deliver 
nursery  stock,  except  when  accompanied  by  a  certifi- 
cate of  inspection  and  the  official  tag  of  the  State 
officer.  All  nursery  premises  must  be  inspected  at 
least  once  a  year. 

West  Virginia. — All  nurseries  must  be  examined 
once  a  year,  not  later  than  August  i5th,  by  the 
Director  of  the  Agricultural  Experiment  Station  of 
Morgantown,  or  by  his  assistants.  Nurserymen  are 
required  to  pay  a  fee  of  $10.00  for  the  first  day's  in- 
spection, and  $5.00  for  each  additional  day  required, 
before  a  certificate  is  given.  The  certificate  is  void 
after  August  i5th  of  the  following  year.  Nurserymen 
must  also  furnish  transportation  to  and  from  railway 
stations  to  their  nurseries.  Any  person  growing  trees 
for  sale  must  apply  to  the  Director  for  a  certificate. 
All  orchards,  gardens,  and  other  premises  where  dan- 
gerous pests  are  supposed  to  exist,  must  be  examined 
and  given  such  treatment  as  may  be  deemed  necessary. 
All  nursery  stock  from  other  States  must  be  properly 
certified,  and  plainly  labeled  with  name  of  consignor 
and  consignee.  In  effect  May  16,  1901. 

Wisconsin. — The  law  in  this  State  requires  that  all 
nursery  stock  entering  shall  bear  certificate  showing 
that  it  has  been  properly  inspected,  and  is  apparently 
free  from  San  Jose  scale  and  other  injurious  insects  or 
plant  diseases.  The  inspection  is  in  charge  of  the 
Agricultural  Experiment  Station  at  Madison,  Wis. 


CHAPTER  XXIII 

FOREIGN    LAWS    REGULATING    SHIPMENTS    OF 
FRUITS  AND   NURSERY  STOCK 

T ""THERE  have  been  so  many  laws  enacted  in  for- 
eign countries  regulating  the  importation 
from  America  of  all  plants  commonly  called 
nursery  stock,  it  is  expedient  to  give  briefly 
an  abstract  of  the  regulations  adopted  by  these  coun- 
tries. These  statements  will  serve  as  a  guide  to  nur- 
serymen and  others  who  contemplate  exporting  nursery 
stock  and  other  supplies. 

Austria- Hungary. — By  a  decree  April  20,  1898, 
prohibits  importation  from  America  of  living  plants, 
grafts  and  layers  and  fresh  plant  refuse  of  every  kind 
if  on  examination  San  Jose  scale  is  found.  It  also  in- 
cludes the  barrels,  boxes,  and  other  coverings  in  which 
such  goods  or  refuse  may  be  packed.  It  embodies 
fresh  fruit  and  the  refuse  of  fresh  fruit,  as  well  as  the 
packings  which  may  cover  the  same.  Admission  lim- 
ited to  Bodenbach-Tetschen,  Trieste  and  Fiume.  Also 
prohibits  transit  of  infested  goods  through  the  Empire. 
Belgium. — Importation  and  transit  of  fresh  fruits, 
living  plants,  and  fresh  parts  of  plants  from  the  United 
States  can  be  made  only  by  way  of  the  ports  of  Ant- 
werp, Ghent,  and  Ostende,  upon  production  of  a  cer- 
tificate from  a  competent  authority  asserting  that 
products  are  not  infested  by  San  Jose  scale.  If  not 
accompanied  by  certificate,  the  products  can  not  be 

303 


304  FUMIGATION   METHODS 

delivered  until  inspected.  If  found  infested  they  must 
be  destroyed  with  packings.  The  cost  of  all  services 
at  the  expense  of  the  importer.  This  order  went  into 
effect  March  15,  1899,  but  does  not  apply  to  shipments 
in  direct  transit  by  railway  under  supervision  of  custom 
authorities. 

British  Columbia. — Rules  and  regulations,  pub- 
lished June  25,  1897,  under  the  authority  of  the  Hor- 
ticultural Board  Act,  1894,  provide  that  all  importers 
of  nursery  stock,  trees,  plants,  or  fruit  must  give 
notice  upon  arrival,  and  before  removal  from  wharf  or 
station,  to  a  member  of  the  Board  or  to  the  Inspector 
of  Fruit  Pests,  who  shall  inspect  the  same  and,  if  clean, 
issue  a  certificate  which  shall  be  good  for  three  months, 
unless  revoked  by  further  inspection.  Nursery  stock 
found  to  be  infected  shall  be  disinfected  or  destroyed. 
Fruit  found  to  be  infected  shall  be  destroyed  or 
reshipped. 

Canada. — According  to  the  San  Jose  scale  act, 
March.  18,  1898,  Canada  prohibits  importation  of  nurs- 
ery stock  from  the  United  States,  Australia,  Japan, 
and  Hawaii.  Stock  imported  in  violation  of  the  law 
will  be  destroyed,  and  the  importer  is  liable  to  a  pen- 
alty of  $200  for  each  offense,  prescribed  by  Section  6 
of  Customs  Tariff.  The  following  exemptions  are 
made  :  Nursery  stock  of  all  kinds  can  be  imported 
from  Europe  without  fumigation,  as  it  is  supposed  the 
San  Jose  scale  has  not  gained  a  foothold  in  European 
countries.  Certain  other  plants,  not  liable  to  the 
attack  of  the  San  Jose  scale,  are  also  exempted  from 
treatment  under  this  act.  These  are:  (i)  green- 


.FOREIGN   LAWS   REGULATING  SHIPMENTS        305 

house  plants,  including  roses  in  leaf  which  have  been 
propagated  under  glass  ;  (2)  herbaceous  perennials, 
including  strawberry  plants;  (3)  herbaceous  bedding 
plants;  (4)  all  conifers;  (5)  bulbs  and  tubers. 

As  all  vegetation  is  much  earlier  in  Oregon  and 
Washington  States,  from  which  most  shipments  are 
made  into  British  Columbia,  it  has  been  arranged  that 
for  that  province  the  fumigating  house  shall  be  kept 
open  for  the  winter  months  from  October  1 5  till  March 
15.  For  Manitoba  and  the  Eastern  Provinces  the 
spring  season  is  from  March  15  till  May  15,  and  the 
autumn  season  from  October  7  till  December  7. 

These  fumigating  houses  are  located  at  the  customs 
ports  of  St.  John,  New  Brunswick;  St.  John's,  Que- 
bec; Niagara  Falls  and  Windsor,  Ontario;  Winnipeg, 
Manitoba;  and  Vancouver,  British  Columbia.  The 
whole  expense  of  these  stations  is  assumed  by  the 
Dominion  Government,  but  all  shipments  are  made 
entirely  at  the  risk  of  the  shippers  or  consignees,  the 
government  assuming  no  risk  whatever.  The  pack- 
ages must  be  addressed  so  as  to  enter  Canada  at  one 
of  the  above-named  ports  of  entry,  and  the  route  by 
which  they  are  to  be  shipped  clearly  stated  upon  each. 

Cape  of  Good  Hope. — Regulations  published  March 
25,  1896,  under  authority  of  act  No.  9,  dated  1896, 
prohibits  importation  of  any  stone-fruit  tree,  or  any 
fruit,  scion,  cutting,  graft,  root,  or  seed,  the  growth 
or  produce  thereof,  from  the  United  States,  and  any  one 
importing  such  article  as  aforesaid  shall  be  subject  to 
a  fine  not  exceeding  £  100  sterling  or  six  months'  im- 
prisonment, and,  in  addition,  the  articles  will  be 
destroyed.  It  is  likely  this  will  be  modified,  especially 


306  FUMIGATION  METHODS 

for  states  in  which  "neither  peach  yellows  nor  peach 
rosette  exists. 

France  prohibits,  decree  of  November  30,  1898, 
entry  into  and  passing  through  France  of  trees,  shrubs, 
products  of  nurseries,  cuttings,  and  all  other  plants  or 
parts  of  living  plants,  as  well  as  fresh  debris  from 
them,  from  United  States,  directly  or  in  storage,  as 
well  as  cases,  sacks,  etc. ,  used  for  packing.  Also  pro- 
hibits fresh  fruit  and  debris,  when  examination  proves 
presence  of  insect  at  entry  into  France. 

GERMANY. — A  decree  of  February  5,  1898,  prohibits 
importation  of  living  plants  and  parts  of  living  plants 
from  America,  and  barrels,  boxes,etc. ,  used  for  packing. 
Also  fresh  fruit  or  fresh  parts  of  fruit  when  examina- 
tion at  port  of  entry  shows  presence  of  San  Jose  scale. 
Imperial  chancellor  authorized  to  grant  exceptions. 

By  commercial  agreement  July  10,  1900,  this  was 
amended  by  annulling  the  regulation  providing  that 
dried  or  evaporated  fruits  from  the  United  States  be 
inspected.  Such  fruits  are  now  admitted  without 
other  charge  than  customs  duties,  and  may  be  admitted 
at  the  boundary  at  the  following  places: 

Prussia. — Main  customs  offices  at  Eydtkuhen,  Pil- 
lau,  Danzig,  L,iebau,  Aachen,  inclusive  of  the  customs 
inspection  office  in  the  depot  of  Templerbend,  and  the 
freight  depot  of  Roth  Erde  ;  Emmerich,  inclusive  of 
the  two  steamship  inspection  offices,  and  the  customs 
inspection  office  located  at  that  place;  Kaldenkirchen, 
inclusive  of  the  customs  inspection  office  at  the  depot 
at  that  place;  Geestemiinde,  Flensburg,  Hadersleben, 
inclusive  of  the  sub-customs  office  i  Woyens;  Kiel  and 


FOREIGN  LAWS  REGULATING  SHIPMENTS       307 

office  at  the  depot  in  L,uxemberg.  Also  main  tax 
offices  at  Konigsberg  i  Pr.  and  Stettin,  and  subcustom 
offices  at  i  Oderberg,  i  Ziegenhals,  i  Halbstadt,  i 
Seidenberg,  Herbesthal,  Bentheim,  Borken,  and 
Weener. 

Bavaria. — Main  customs  offices  at  landau,  Passau, 
Simbach,  and  subcustoms  office  at  Scharding  a.  Th., 
and  Furth  a.  W.  Also  subcustoms  offices  at  Kufstein, 
Salzburg,  Kger,  Obernzell,  and  at  the  depot  of 
Kisenstein. 

Kingdom  of  Saxony. — Main  custom  offices  atZittau 
and  Schandau;  subcustoms  offices  at  Bodenbach  and 
Tetschen,  Voitersreuth,  Reitzenhain,  and  i  Warnsdorf. 

Wiirttemberg. — Main  customs  office  at  Friedrich- 
shafen. 

Baden. — Main  customs  offices  at  Konstanz,  the 
depots  of  Schafthausen  and  Waldshut,  and  at  the  depot 
of  Basel ;  main  tax  office  at  Singen  and  Seckingen, 
and  subcustom  office  at  Erzingen. 

Oldenburg. — Subcustoms  office  at  i  Nordenham. 
Liibeck. — Main  customs  house  at  L,iibeck. 

Bremen. — Ports  of  entry  at  Bremen  and  Bremer- 
haven. 

Hamburg. — Quay  office,  Hamburg. 

Alsace-Lorraine. — Subcustoms  offices  at  Fentsch, 
Amanweiler,  Noveant,  Chambrey,  Deutsch-Avri- 
court,  Altmiinsterol,  Basel,  Markirch,  Saales,  Diedols- 
hausen,  and  Urbis. 


308  FUMIGATION   METHODS 

Netherlands. — By  decree  of  May  23,  1899,  prohibits 
importation  and  transit,  direct  or  indirct,  of  live  trees 
and  shrubs,  or  live  parts  thereof,  produced  in  America, 
including  boxes,  casks,  baskets,  sacks,  vessels,  and 
other  articles  used  for  packing,  unless  accompanied  by 
certificate  issued  by  consular  officer  of  Netherlands  or 
competent  authority  in  port  of  shipment,  and  objects 
shall  not  be  landed  unless  certificate  is  satisfactory  to 
receiver  of  import  duties. 

The  following  exceptions  are  made:  (i)  Importa- 
tions from  countries  bordering  on  the  Netherlands  in 
which  measures  have  been  taken  for  combating  the 
San  Jose  scale;  (2)  importations  for  scientific  purposes; 
and  (3)  to  meet  requirements  of  frontier  commerce. 

New  Zealand. — The  act  of  1896  prohibits  impor- 
tation of  fruit  of  any  kind  infested  with  fruit-flies. 
Fruit  infested  with  codling  moth  will  be  destroyed 
unless  immediately  reshipped.  Fruit,  plants,  trees, 
cuttings  or  buds  infested  with  any  scale  insect  will  be 
admitted  only  when  accompanied  by  certificate.  Other- 
wise it  will  be  fumigated  at  expense  of  importer  or 
destroyed. 

Imported  fruit  admitted  only  at  Bluff,  Dunedin, 
Christchurch,  Wellington,  and  Auckland. 

Live  plants  admitted  only  at  Dunedin,  Christchurch, 
Wellington,  and  Auckland. 

Fumigation  performed  only  at  Dunedin,  Christ- 
church,  Wellington,  and  Auckland. 

Switzerland. — Prohibits  plants;  prohibits  importa- 
tion of  fresh  fruit  from  America,  except  through 
Customs  Bureau  at  Basle,  where  it  is  subject  to  an 
examination  by  an  expert  for  San  Jose  scale  or  other 


FOREIGN   LAWS   REGULATING  SHIPMENTS        309 

parasites.     No   restri(5lions   to   dire(5l    importation   of 
dried  fruits. 

Turkey. — In  1899  it  was  stated  that  the  imperial 
government  had  decided  to  interdicl  the  importation 
of  trees,  plants,  and  fruits  coming  from  the  United 
States.  The  writer  has  made  every  effort  to  obtain 
copies  of  the  decree,  but  has  been  unable  to  secure 
anything  more  definite  than  the  above. 


INDEX 


PAGE 

Actinic  rays 6 

Alkali  action  on 11 

Apparatus,  Orchard 27 

Apple  trees 16 

Arkansas 229 

Arizona 229 

Bell  tents 27,35 

Black  scale 80 

Box,  Fumigation 8,  96,  238 

Brown  scale 80 

Buds 214 

Building 165 

Cabbage 150 

Cacti 136 

California 54,  223 

Canada 229 

Cantaloups 24 

Cape  Colony 211 

Carbon  bisulphid 153 

Action  in  soils 263 

Amount  to  use 266,  270,  277 

Ants  in  lawns 268 

Application,  when 265 

Borers  in  trees 269 

Chemical  properties 258 

Clothes 276 

Commercial  uses 261 

Diffusion 264 

Effects  on  fruits 275 

Extra  precaution 273 

Fidia  viticida 268 

First  use 2,  257 

Flour  moth 280 

France 262 

Furs  .- 276 

Germination  of  seeds 273 

Gophers 277 

Ground  moles 282 

Household  pests 276 

How  put  up 284 

In  the  arts 262 

Inhaling  gas 259 

Instruments  for  application...  266 

Insurance  companies 281 

Melon  plant-lice 269 

Method  of  application  270 

Mice  destroyed 283 

Mills  and  other  buildings 270 

Mole  cricket 268 

Phylloxera 262 

Prairie-dogs .  . .   277 


PAGE 
Carbon  bisulphid—  Continued 

Rats  destroyed 283 

Root-maggots 267 

Root- worms 267 

Squirrels. 277 

Stimulating  effects  on  plants.  274 

Time  to  do  work 271 

Treatment  of  seeds 274 

Vapor 259,  280 

Weevils 282 

White  grubs 268 

Woodchucks 282 

Woolens 276 

Wyoming 278 

Carnations 135 

Cars 166 

Certificates 232,  235 

Chemicals 9 

Comparative  value  of  cyanide.    83 

Cost  of 66 

Estimating  amount. 76,  77, 118, 162 
Estimating     for     California 

orchards 78 

Estimating     for   Eastern    or- 
chards      83 

Needed  on  damp  ground 81 

Cold  frames 144 

Coleus 134 

Connecticut 236 

Conservatories 200 

Cottony  cushion  scale 1 

Criminals 221 

Cucumbers 24, 150 

Culver  fumigator 27,  81 

Cuttings 199 

Daylight  fumigation 84 

Deadly  nature 25 

Deposits  forming 11 

Diffusion 114,  186, 189, 193 

Dry  gas  process 4 

Dwelling-house 166 

Economic  use 1 

Effects  on  animal  life 25 

Elevators 153, 170 

Emory  fumigator 8,  28,  59 

England 198 

Explosive  properties 167 

Ferns 133 

Florida 236 

Foliage 3, 127,  192 

311 


3I2 


FUMIGATION    METHODS 


•AGE 

Fresh  earth 192 

Fumigation,  Cost  of 89,  119,  247 

Equipment 93 

Figures  209 

Materials  needed 121 

Value  of 221 

vs.  Spraying 226 

FuHiigatoriurn 97,  98,  99,  104 

109,  110 

Fu  mi  gator,  box  type 72 

Box  used  in  Canada 95 

Box  used  in  South 94 

Cost 66.  71,  75 

Lowe  type 74 

Miller  type 67 

Sirrine  type 216 

Generating 4,9,115,  160,  164 

Generator,  position 113 

Good  points 154 

Grain 153,  177 

Grapes 127,  136 

Greenhouses. ...  15, 126, 136, 140,  145 
202,  203,  224 

Help  required 66 

Hoop  tent 41,  89 

Houses 174 

Idaho 238 

Insects  in  mills 158,  161 

Jars,  Preparing 130 

June  buds 22 

Laboratory 174 

Ladybirds— Introduction 5 

Laws 285 

Alsace-Lorraine 307 

Austria-Hungary 303 

Baden 307 

Bavaria 307 

Bremen 307 

British  Columbia 304 

California 287 

Canada 230,  304 

Cape  of  Good  Hope 305 

Colorado 287 

Connecticut 287 

Delaware 288 

Florida 288 

France 306 

Georgia 289 

Germany 306 

Hamburg 307 

Idaho 289 

Illinois 290 

Indiana 290 

Iowa 290 

Kentucky 290 

Kingdom  of  Saxony 307 

Louisiana 291 


PAGE 
Laws — Continued. 

Liibeck 307 

Maryland 291 

Massachusetts 292 

Michigan 292 

Missouri \ 293 

Montana 293 

Netherlands 308 

New  Jersey 295 

New  York 295 

New  Zealand 308 

North  Carolina 296 

Ohio 297 

Oldenberg 307 

Oregon 298 

Pennsylvania 299 

Prussia  . .., 306 

South  Carolina 299 

Switzerland 308 

Tennessee. .  .t 300 

Turkey 309 

Utah 301 

Virginia 301 

West  Virginia 302 

Wisconsin 302 

Wurttemberg 307 

Leaf  buds 11 

Leaf -rollers 24 

Lemons 254 

Lettuce 24 

Lifter 52 

Louisiana...  ..  239 


Mandarin 254 

Massachusetts 239 

Mealy  bugs 203 

Mechanical  mixer 191 

Melons 150 

Michigan 239 

Mills 8,  155,159,  170 

Mississippi 240 

Missouri 240 

Morse  f  umigator 28,  32 

Nebraska 241 

New  Jersey 242 

New  South  Wales 203,  252 

New  York 212, 242 

Night  fumigation 6 

North  Carolina 241 

North  Dakota 242 

Nursery  stock 42,  16,  223,  232 

Nurserymen,  Points  for 123 


Objectors 246 

Ohio 243 

Olive  trees 225 

Ontario 233 

Oranges 253 

Orchard  trees 7,  65,  218,  234 


INDEX 


313 


Paint 31 

Palm  scale 229 

Peach  trees 20 

Pennsylvania 243 

Plants 135,  150 

Plum  trees 15, 19 

Preble  f  umigator 36 

Purple  scale 80 


Red  scale 5,  80,  227 

Residue 11,  166 

Rhode  Island 244 

Root  aphis 24 

22,  135 


San  Jos6  scale 7 

Scale  insects,  Aspidiotus  auran- 

tii 5 

Aspidiotus  ficus 224 

Aspidiotus  perniciosus 7 

Icerya  purchasi 2 

Seeds 24,  177, 180,  181 

Sheet  tent,  Construction 48 

Covering  orange  tree 51 

Management 48 

Removing  with  horse 55 

Ships 166 

Small  plants 132 

Soda  process 3 

Strawberry  plants 24,  147 

Sulphur  fumes 153 


PAGE 

Tents,  Adjusting  hoop 41 

Canvas 27,  32 

Care  91 

Construction 28 

Cost 30,  206 

Covering  tree 44 

Manipulating 48 

Materials 28,  206 

Oiling  and  painting 31 

Raising 35 

Removing 39 

Sheet 31 

Size 28 

Testimonials 168 

Titus  f  umigator 27 

Tobacco  fumes 153 

Warehouses 169 

Tomatoes 136 

Trees 4, 120 

Utah... 


251 

Value 1 

Vegetable  houses 139 

Ventilators 112 

Vessels 10 

Vineries 200 

Violets 127,134,146 

Virginia 245 

Wagon 91 

Winter  treatment 213 

Wolf  skill  f  umigator 27 


Works  at: 


Perth  Amboy 
New  Jersey 


Cyanide  of  Potassium 

Guaranteed  ?8/99  per  cent. 


FOR    GENERATING 


Hydrocyanic  Acid  Gas 

THE    MOST    EFFECTIVE 

FUMIGATING     MATERIAL 

To  Destroy  Scale  Insects  on  Fruit  Trees,  Nur- 
sery Stock,  and  Plants  of  all  kinds  under 
Glass  and  in  Greenhouses;  also  Insects  in 
Mills,  Elevators,  Warehouses,  Cars,  Ships,  etc. 


...  Manufactured  by  the  ... 

Roessler    6    H&>ssl&.cher  Chemical    Co. 

100    William  Street,    New    York 


FUM  A 

CARBON    BISULPHID 


Creates  a  death  atmosphere  in  which 
no  animal  life  can  exist 

"The  wheels  of  the  gods  grind  slow  but  exceeding 
small."  So  do  weevil,  but  don't  let  them  grind  your  grain. 
Kill  them  with  "FUMA,"  as  others  are  doing. 

I  reach  the  consumer  direct,  and  FUMA  reaches  all  insect 
pests  in  stored  grains  and  seeds,  and  gophers,  prairie-dogs, 
woodchucks  and  ants  in  the  field. 

"  A  simple,  effective,  and  comparatively  cheap  remedy  for  insect  pests 
in  stored  grain  is  FUMA  CARBON  BISUIyPHID."— Prof.  W.  G.JOHNSON. 

Orders  for  FUMA  come  from  practical  men  every  day. 

EDWARD  R.  TAYLOR,  Penn  Yan,  N.  Y. — Dear  Sir:  Four  years  ago 
we  were  bothered  with  weevil.  We  bought  five  gallons  of  FUMA  and  it 
did  the  work.  Ship  at  once  (Sept.  3,  1901)  five  gallons  more  of  the  same 
stuff.  Yours  very  truly,  HENRY  W.  HUNT,  Palmyra,  Wis. 

WELLAND,  ONT.,  Sept.  19,  1901. — Dear  Sir:  The  last  FUMA  sent  us 
has  done  the  business.  Occasionally  we  find  bugs  on  bags,  etc.,  but  they 
are  dead.  In  bins  we  used  cotton-waste  balls  well  saturated  with  FUMA 
instead  of  plates,  as  before.  We  also  poured  FUMA  around  spouts  and  on 
wheat,  which  in  our  opinion  is  the  safest  way  of  exterminating  the  pests. 
—BROWN  BROS. 

A  bit  of  cotton,  rags,  dry  horse-manure  balls,  or  even 
grass,  saturated  with  about  two  tablespoonfuls  of  FUMA,  and 
thrust  into  the  burrow  of  a  gopher  or  squirrel,  will  kill  them 
every  time. 

Do  not  ask  dealers  to  make  you  prices,  but  write  to  me. 

Price  of  FUMA,  f.  o.  b.  cars  at  Penn  Yan,  N.  Y.,  in  50-pound 
steel  drums,  10  cents  per  pound.  Cash  must  accompany  the 
order. 

For  minute  directions  for  using  and  applying  FUMA  see 
CHAPTER  XXI.  in  this  book  ;  but  write  to 

EDWARD  R.  TAYLOR, 

Manufacturing'  Chemist, 

Penn  Yan,  N.  Y., 

,..AND  GET  THE  ONLY  GENUINE... 


FUMA 


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all  available  sources,  the  ideas  and  conclusions  of  the  most  practical, 
successful,  and  observant  men  who  have  followed  the  business  in  our 
time,  and  in  our  own  country,  acting  upon  the  belief  that  no  one 
man,  or  any  half-dozen  men,  know  all  there  is  worth  knowing  on  a 
subject  so  extensive  and  important  as  that  of  Swine  Husbandry.  It 
is  the  fullest  and  freshest  compendium  relating  to  swine  breeding  yet 
offered.  Cloth,  i2tno.  Illustrated.  $1.50. 

Home  Pork  Making 

The  art  of  raising  and  curing  pork  on  the  farm.  By  A.  W.  FULTON. 
A  complete  guide  for  the  farmert  the  country  butcher,  and  the 
suburban  dweller,  in  all  that  pertains  to  hog  slaughtering,  curing, 

Preserving,  and  storing  pork  product— from  scalding  vat  to  kitchen 
ible  and  dining-room.    Fully  illustrated.    Cloth.    50  cents. 

Shepherd's  Manual 

By  HENRY  STEWART.  A  practical  treatise  on  the  sheep  for  Ameri- 
can farmers  and  sheep-growers.  The  results  of  personal  experience 
of  many  years  with  the  characters  of  the  various  modern  breeds  of 
sheep,  and  the  sheep-raising  capabilities  of  the  United  States  and 
Canada — and  the  careful  study  of  the  diseases  to  which  our  sheep  are 
chiefly  subject,  with  those  by  which  they  may  eventually  be  afflicted 
through  unforeseen  accidents — as  well  as  the  methods  of  management 
called  for  under  our  circumstances,  are  here  gathered.  Illustrated. 
Cloth,  i2mo.  $1.00. 

Cabbage,  Cauliflower,  and  Allied  Vegetables 

By  C.  Iy.  ALLEN.  A  practical  and  reliable  guide  to  the  successful 
raising  of  cabbage,  cauliflower,  broccoli,  collards,  Brussels  sprouts, 
kale,  and  kohlrabi,  from  "seed  to  harvest."  Illustrated.  5x8  inches, 
128  pages.  Cloth.  50  cents. 

Hedges,  Windbreaks,  Shelters,  and  Live  Fences 

By  E.  P.  POWELL.  The  planting,  growth,  and  management  of  hedge 
plants  for  country  and  suburban  homes.  Illustrated.  5x8  inches, 
140  pages.  Cloth.  50  cents. 

Landscape  Gardening 

By  F.  A.  WAUGH.  A  treatise  on  the  general  principles  governing 
outdoor  art,  with  sundry  suggestions  for  their  application  in  the 
commoner  problems  of  gardening.  Illustrated.  5x8  inches,  150  pages. 
Cloth.  50  cents. 

Plums  and  Plum  Culture 

By  Prof.  F.  A.  WAUGH.  A  complete  manual  for  fruit-growers, 
nurserymen,  farmers,  and  gardners,  on  all  known  varieties  of  plums 
and  their  successful  management.  A  monograph  of  the  plums  culti- 
vated in  and  indigenous  to  North  America,  with  a  complete  account 
of  their  propagation,  cultivation,  and  utilization.  It  is  one  of  the 
most  complete,  accurate,  and  satisfactory  works  ever  written  for  the 
field  of  American  horticulture.  Illustrated.  5x8  inches,  371  pages. 
Cloth.  $1.50. 

Hemp  (Cannabis  sativa) 

By  S.  S.  BOYCE.  A  practical  treatise  on  the  culture  of  hemp  for  seed 
and  fiber,  with  a  sketch  of  the  history  and  nature  of  the  hemp  plant. 
All  the  various  operations  connected  with  hemp  culture  are  so  plainly 
and  clearly  described  as  to  enable  any  one  to  make  a  success  of  hemp- 
raising.  Illustrated.  5x8  inches,  122  pages.  Cloth.  50  cents. 


Ginseng— Its  Cultivation,  Harvesting,  Marketing,  and  Mar- 
ket Value. 

By  MAURICE  G.  KAINS,  with  a  short  account  of  its  history  and  bot- 
any. It  discusses  in  a  pi»ctical  way  how  to  begin  with  either  seed  or 
roots,  soil,  climate  and  location,  preparation,  planting  and  mainte- 
nance of  the  beds,  artificial  propagation,  manures,  enemies,  selection 
for  market  and  for  improvement,  preparation  for  sale,  and  the  profits 
that  may  be  expected.  The  booklet  is  concisely  written,  well  and 
profusely  illustrated,  and  should  be  in  the  hands  of  all  who  expect 
to  grow  this  drug  to  supply  the  export  trade,  and  to  add  a  new  and 
profitable  industry  to  their  farms  and  gardens,  without  interfering 
with  the  regular  work.  i2tno.  35  cents. 

Land  Draining. 

By  MANLY  MILES.  A  handbook  for  farmers  on  the  principles  and 
practice  of  draining,  giving  the  results  of  his  extended  experience  in 
laying  tile  drains.  The  directions  for  the  laying  out  and  the  con- 
struction of  tile  drains  will  enable  the  farmer  to  avoid  the  errors  of 
imperfect  construction  and  the  disappointment  that  must  necessarily 
follow.  Cloth,  i2mo.  $1.00. 

Practical  Forestry. 

By  ANDREW  S.  FULLER.  A  treatise  on  the  propagation,  planting 
and  cultivation,  with  descriptions  and  the  botanical  and  popular 
names  of  all  the  indigenous  trees  of  the  United  States,  and  notes  on 
a  large  number  of  the  most  valuable  exotic  species.  $1.50. 

Mushrooms.     How  to  Grow  Them. 

By  WILLIAM  FALCONER.  This  is  the  most  practical  work  on  the 
subject  ever  written,  and  the  only  book  on  growing  mushrooms  pub- 
lished in  America.  The  author  describes  how  he  grows  mushrooms, 
and  how  they  are  grown  for  profit  by  the  leading  market  gardeners, 
and  for  home  use  by  the  most  successful  private  growers.  Engra- 
vings drawn  from  nature  expressly  for  this  work.  Cloth.  $1.00. 

The  Propagation  of  Plants. 

By  ANDREW  S.  FULLER.  Illustrated  with  numerous  engravings. 
An  eminently  practical  and  useful  work.  Describing  the  process  of 
hybridizing  and  crossing,  and  also  the  many  different  modes  by 
which  cultivated  plants  may  be  propagated  and  multiplied.  Cloth, 
i2ino.  $1.50. 

Silos,  Ensilage,  and  Silage. 

By  MANLY  MILES,  M.D.,  F.R.M.S.  A  practical  treatise  on  the  ensi- 
lage of  fodder  corn.  Containing  the  most  recent  and  authentic  infor- 
mation on  this  important  subject.  Illustrated.  Cloth,  i2mo.  50 
cents. 

Play  and  Profit  in  My  Garden. 

By  E.  P.  ROE.  The  author  takes  us  to  his  garden  on  the  rocky  hill- 
sides in  the  vicinity  of  West  Point,  and  shows  us  how  out  of  it,  after 
four  years'  experience,  he  evoked  a  profit  of  $1,000,  and  this  while 
carrying  on  pastoral  and  literary  labor.  It  is  very  rarely  that  so 
much  literary  taste  and  skill  are  mated  to  so  much  agricultural  ex- 
perience and  good  sense.  Cloth,  i2mo.  $ i.oo. 

Grape  Culturist. 

By  ANDREW  S.  FULLER.  This  is  one  of  the  very  best  of  works  on 
the  culture  of  the  hardy  grapes,  with  full  directions  for  all  depart- 
ments of  propagation,  culture,  etc.,  with  150  excellent  engravings, 
illustrating  planting,  training,  grafting,  etc.  Cloth,  i2mo.  $1.50. 


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